Urethane resin particles for slush molding

ABSTRACT

Provided are urethane resin particles for slush molding which make it possible that inconveniences based on the slip-down of a pigment, on the aggregation of particles of the pigment, and on other causes are removed although this coloring is coloring onto the resin particle surfaces. The present invention is urethane resin particles for slush mold which contain a urethane resin and an additive, wherein the particles have a shape factor SF 1  of 101 to 200, a shape factor SF 2  of 120 to 240, and a central particle diameter of 20 to 500 μm. It is preferred that the urethane resin has a concentration of urea groups of 0.5 to 10% by weight, a total of the concentration of urethane groups and that of the urea groups of 4 to 20% by weight, a melting point of 160 to 260° C. and a glass transition temperature of −65 to 0° C.

TECHNICAL FIELD

The present invention relates to urethane resin particles for slushmolding having irregular surfaces.

BACKGROUND ART

In recent years, a slush molding method has widely been used forinterior materials and the like of automobiles, since the molding makesit possible to mold easily into a product having a complicated form(such as an undercut or deep drawn form) and give an even wallthickness, and makes the yield percentage of the raw material good.Conventionally, in many cases, slush molding powdery products of a vinylchloride-based resin have been used as skin materials of automobileinterior components such as an instrument panel and a door trim.

However, when a vinyl chloride-based material is used over along term, aplasticizer contained therein shifts to the surface thereof inaccordance with a use environment thereof, so that the material isdamaged in soft feeling. When an automobile is disposed and thensubjected to incineration treatment, hydrogen chloride gas is generatedin accordance with the incineration temperature, so that theincineration furnace may be corroded in some cases.

In order to solve these problems, developments are being advanced abouta slush molding powdery material comprising a thermoplastic resin otherthan vinyl chloride. Use is made of, for example, a thermoplasticpolyurethane elastomer having a number-average molecular weight of20,000 to 50,000 and a glass transition temperature of −35° C. or lower(Patent Document 1).

Use is also made of a granular polyurethane resin composition mademainly of a thermoplastic urethane resin synthesized in a non-aqueousdispersion medium, a polymer of a vinyl monomer, and a thermallycrosslinkable monomer (Patent Document 2). Furthermore, use is made of athermoplastic elastomer composition powder having a particle diameter of1 to 1000 μm and comprising an acrylic block copolymer and an acrylicpolymer having, in a single molecule thereof, reactive functional groupsthe number of which is 1.1 or more (Patent Document 3).

In a material for slush molding, a colored material is used as a skinmaterial of an automobile interior component in order to cause thecomponent to exhibit high quality feeling. These materials for slushmolding, each comprising a thermoplastic resin, are also colored bysynthesizing uncolored particles, and then dusting a coloring agent suchas an inorganic pigment or an organic pigment onto the surfaces thereof.In this coloring method, however, by shear at the time of stirring andmixing in the step of the coloring or in a step subsequent thereto,particles of the pigment which adhere onto the resin particle surfacesare slipped down from the surfaces, or the pigment particles areaggregated with each other on the particle surfaces. Thus, this methodhas a problem that the original color of the coloring agent is notexpressed, a lump of the pigment is intermingled with the resultantproduct, or the like.

In order to solve such a problem, suggested is a method in which beforea resin is granulated, a liquid prepolymer for the resin is mixed with acoloring agent, and subsequently the mixture is granulated (PatentDocument 4).

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP 11-49948 A-   Patent Document 2: JP 2009-91519 A-   Patent Document 3: JP 2009-67853 A-   Patent Document 4: JP 2005/097901 A1

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

In the method in which before a resin is granulated, a liquid prepolymerfor the resin is mixed with a coloring agent, and subsequently themixture is granulated, particles of the pigment are incorporated intothe resin particles, so that the pigment is not slipped down from theresin particles, and the pigment particles are not aggregated with eachother on the particle surfaces; however, when the method is comparedwith the above-mentioned method of coloring particle surfaces, thismethod is poorer in productivity since it is unavoidable to washproduction facilities carefully whenever the color of products ischanged.

An object of the present invention is to provide urethane resinparticles for slush molding which make it possible that inconveniencesbased on the slip-down of a pigment, on the aggregation of particles ofthe pigment, and on other causes are removed although this coloring iscoloring onto the resin particle surfaces, and which are high inproductivity.

Means for Solving the Problems

The present inventors have made eager investigations to yield resinparticles as described above, so as to find out that fine irregularitiesare made in surfaces of particles, and a coloring agent is added to theirregular-surface particles, thereby making it possible to fix thepigment particles into depressions in the surfaces, so that theparticles can be colored without causing the slip-down of the pigment orthe aggregation of the particles thereof. Thus, the present inventionhas been attained.

Accordingly, the present invention is urethane resin particles (C) forslush mold, which comprise a urethane resin (D) and an additive (N), andwhich have a shape factor SF1 of 101 to 200, a shape factor SF2 of 120to 240, and further a central particle diameter of 20 to 500 μm; aprocess for producing the urethane resin particles (C); a method forcoloring the urethane resin particles (C); and a urethane resin moldedbody obtained by subjecting the urethane resin particles (C) to slushmolding.

Effects of the Invention

The use of the urethane resin particles (C) of the present invention forslush molding makes it possible that inconveniences based on theslip-down of a pigment, on the aggregation of particles of the pigment,and on other causes are removed although this coloring is coloring ontothe resin particle surfaces.

MODE FOR CARRYING OUT THE INVENTION

The urethane resin particles (C) of the present invention for slushmolding have a shape factor SF1 of 101 to 200, and a shape factor SF2 of120 to 240.

The urethane resin particles (C) have irregular surfaces, so that theSF1 is 101 or more. Particles having a shape factor SF1 of more than 200have an irregular shape to be deteriorated in powder fluidity.

If particles have a shape factor SF2 of less than 120, even when acoloring agent is added to the particles so that particles of thepigment are fixed onto the surfaces, the pigment particles on thesurfaces are slipped down by shear generated when the particles arestirred in a subsequent step; and further the pigment particles areaggregated with each other so that the original color thereof is notdeveloped. When the pigment particle aggregates become large, theaggregates turn into alien substances to deteriorate the quality of theproduct. On the other hand, particles having a SF2 of more than 240,irregularities in the surfaces are too fine so that the pigment does noteasily enter gaps in the irregularities so that the particles aredeteriorated in pigment-dispersion stability.

The shape factor SF1 is a factor representing the roundness of the shapeof a particle, is a value obtained by projecting a urethane particleonto a two-dimensional plane, dividing the square of the longestdiameter of the resultant figure by the area AREA of the figure and thenmultiplying the resultant value by 100π/4, and is represented by thefollowing expression (1) :SF1={(longest diameter)²/(AREA)}×(100π/4)   (1)

When the value of the SF1 is 100, the shape of the urethane particle isa complete sphere. As the SF1 value becomes larger, the particle becomesmore irregular in shape.

The shape factor SF2 is a factor representing the proportion ofirregularities in the shape of a particle, is a value obtained byprojecting a urethane particle onto a two-dimensional plane, dividingthe square of the peripheral length PERI of the resultant figure by thearea AREA of the figure and then multiplying the resultant value by100/4π, and is represented by the following expression (2):SF2={(PERI)²/(AREA)}×(100/4π)   (2)

When the value of the SF2 is 100, the surface of the urethane particlehas no irregularities. As the SF2 value becomes larger, irregularitiesin the urethane particle surface become more remarkable.

Examples of the method for measuring the shape factors SF1 and SF2include a method of taking a photograph of urethane particles by meansof a scanning electron microscope (for example, S-800, manufactured byHitachi Ltd.), a microscope (USB Digital Scale, manufactured by ScalarCorporation), or some other, and introducing this photograph into animage analyzing device (for example, LUSEX 3, manufactured by NirecoCorporation) to make analysis, and a method of using a flow-modeparticle image analyzer (for example, FPIA-3000, manufactured by SysmexCorporation) to make a measurement.

The urethane resin particles (C) have a central particle diameter of 20to 500 μm, preferably from 30 to 400 μm, more preferably from 50 to 300μm.

If the particles (C) have a central particle diameter of less than 20μm, the particles deteriorate in powder fluidity, so that the particlesdeteriorate in moldability or easily cause the generation of dust whensubjected to slush molding. Thus, the operating environmentdeteriorates. If the particles (C) have a central particle diameter ofmore than 500 μm, the shape of the powder that has not been leveledremains after the slush molding, or many pinholes are generated in themold surfaces.

The central particle diameter referred to herein is a volume-averageparticle diameter, which is the value of the below-sieve 50% particlediameter measured by a laser-light scattering method. An example of aninstrument for the measurement is a Microtrac HRA Particle Size Analyzer9320-X100 (manufactured by Nikkiso Co., Ltd.).

In the urethane resin particles (C) of the present invention, the ratioof the 90% particle diameter to the 10% particle diameter is preferablyfrom 2.0 to 3.0. As used herein, the ratio of the 90% particle diameterof the particles to the 10% particle diameter thereof is a valueobtained by dividing the 90% particle diameter by the 10% particlediameter. When this ratio is in this range, the particles are suitablefor slush molding, and the number of pinholes is small on the moldsurfaces after subjected to slush molding. Moreover, the particles aregood in powder fluidity, and the step of classifying the particlesbecomes unnecessary.

The urethane resin (D), which constitutes the urethane resin particles(C) of the present invention, preferably has a concentration of ureagroups of 0.5 to 10% by weight, a total of the concentration of urethanegroups and that of the urea groups of 4 to 20% by weight, a meltingpoint of 160 to 260° C. and a glass transition temperature of −65 to 0°C.

Urea groups remarkably improve the urethane resin (D) in strength,solvent resistance, and abrasion resistance; thus, when the urethaneresin (D) contains urea groups, the urea groups can largely improveperformances of the urethane resin particles (C). The concentration ofthe urea groups is preferably from 0.5 to 10% by weight, more preferablyfrom 1.0 to 7.0% by weight, and most preferably from 1.5 to 5.0% byweight.

When the concentration of the urea groups is in the range of 0.5 to 10%by weight, remarkable is an effect that the urea groups improve thestrength, the solvent resistance and the abrasion resistance.Additionally, when the urethane resin particles (C) are molded andprocessed, the melting point and the melt viscosity thereof arerestrained into low values, so that thermal energy required for themolding can be decreased.

Simultaneously, urethane groups also improve performances of theurethane resin (D), similarly to the urea groups. Thus, the total of theconcentration of the urethane groups and that of the urea groups ispreferably from 4 to 20% by weight, more preferably from 6 to 15% byweight, and most preferably from 8 to 12% by weight.

In the present invention, the concentration of the urethane groups, andthat of the urea groups are the concentration represented by “% byweight” of the urethane groups in the urethane resin (D), and thatrepresented by “% by weight” of the urea groups in the urethane resin(D), respectively.

The urethane resin (D), which constitutes the urethane resin particles(C) of the present invention, preferably has a melting point of 160 to260° C., more preferably of 210 to 250° C. When the melting point rangesfrom 160 to 260° C., the particles are excellent in blocking property inan ordinary preserving environment, and further thermal energy at thetime of molding can be decreased.

The (D) preferably has a glass transition temperature of −65 to 0° C.,and more preferably of −50 to −10° C. When the glass transitiontemperature ranges from −65 to 0° C., the particles can have impactresistance even at a lower temperature.

Examples of the urethane resin (D) in the present invention includeresins yielded by causing an isocyanate group-terminated urethaneprepolymer (a) derived from an aliphatic diisocyanate (a1), a monool(a2), a high molecular weight diol (a3) having a number-averagemolecular weight of 500 to 10,000, and a low molecular weight diol (a4)if necessary to react with an alicyclic diamine and/or an aliphaticdiamine (b).

Examples of the aliphatic diisocyanate (a1) constituting theabove-described (a) include (i) aliphatic diisocyanates having 2 to 18carbon atoms (the carbon atoms in the NCO groups are excluded;hereinafter, the same shall apply hereinafter) [such asethylenediisocyanate, tetramethylenediisocyanate,hexamethylenediisocyanate (HDI), dodecamethylenediisocyanate,2,2,4-trimethylhexamethylenediisocyanate, lysinediisocyanate,2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl) fumarate,bis(2-isocyanatoethyl) carbonate, and2-isocyanatoethyl-2,6-diisocyanatohexanoate]; (ii) alicyclicdiisocyanates having 4 to 15 carbon atoms [such asisophoronediisocyanate (IPDI), dicyclohexylmethane-4,4′-diisocyanate(hydrogenated MDI), cyclohexylenediisocyanate,methylcyclohexylenediisocyanate (hydrogenated TDI), andbis(2-isocyanatoethyl)-4-cyclohexene]; (iii) aromatic aliphaticdiisocyanates having 8 to 15 carbon atoms [such as m- and/orp-xylylenediisocyanate(s) (XDI), andα,α,α′,α′-tetramethylxylylenediisocyanate (TMXDI)]; (iv) modifiedproducts of these diisocyanates (modified diisocyanates each having acarbodiimide group, a urethodione group, a urethoimine group, a ureagroup, or some other group); and mixtures of two or more thereof.

Of these examples, preferred are aliphatic diisocyanates, or alicyclicdiisocyanates, and particularly preferred are HDI, IPDI and hydrogenatedMDI.

Examples of the above-described monool (a2) include aliphatic monoolshaving 1 to 8 carbon atoms [such as linear monools (such as methanol,ethanol, propanol, butanol, pentanol, hexanol, and octanol), and monoolshaving a branched chain (such as isopropyl alcohol, neopentyl alcohol,3-methyl-pentanol, and 2-ethylhexanol)]; monools having a cyclic groupof 6 to 10 carbon atoms [such as alicyclic group-containing monools(such as cyclohexanol), and aromatic ring-containing monools (such asbenzyl alcohol)], and mixtures of two or more thereof.

Of these examples, preferred are aliphatic monools. Examples of themonool that is a high molecular weight monool include polyester monools,polyether monools, polyetherester monools, and mixtures of two or morethereof.

Examples of the high molecular weight diol (a3), which has anumber-average molecular weight of 500 to 10,000, include polyesterdiols, polyether diols, polyetherester diols, and mixtures of two ormore thereof.

Examples of the polyester diols include (i) diols each produced bycondensation polymerization of a low molecular weight diol, and adicarboxylic acid or an ester-formable derivative thereof [such as anacid anhydride, a lower alkyl (the number of carbon atoms: 1 to 4)ester, or an acid halide], or a dialkyl carbonate (the number of carbonatoms in each of the alkyl groups: 1 to 4); (ii) diols each produced byring opening polymerization of a lactone monomer, using a low molecularweight diol as an initiator; (iii) diols each produced by causing adicarboxylic acid anhydride, and an alkylene oxide to react with eachother, using a low molecular weight diol as an initiator; and mixturesof two or more thereof.

Specific examples of the low molecular weight diols in theabove-described (i), (ii) and (iii) include aliphatic diols having 2 to8 carbon atoms [such as linear diols (such as ethylene glycol,diethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and1,6-hexanediol), and diols having a branched chain (such as propyleneglycol, neopentyl glycol, 3-methyl-1,5-pentanediol,2,2-diethyl-1,3-propanediol, and 1,2-, 1,3- or 2, 3-butanediol) ]; diolscontaining a cyclic group [such as diols having an alicyclic group of 6to 15 carbon atoms [such as 1,4-bis(hydroxymethyl)cyclohexane, andhydrogenated bisphenol A], diols containing an aromatic ring of 8 to 20carbon atoms (such as m- or p-xylylene glycols), oxyalkylene ethers ofbisphenols (such as bisphenol A, bisphenol S and bisphenol F),oxyalkylene ethers of polynuclear phenols (such asdihydroxynaphthalene), and bis(2-hydroxyethyl)terephthalate]; andalkylene oxide adducts thereof (molecular weight: less than 500), andmixtures of two or more thereof.

Of these examples, preferred are aliphatic diols and alicyclicgroup-containing diols.

Here, examples of the alkylene oxide include ethylene oxide (EO),propylene oxide (PO), 1,2-, 1,3-, 1,4- or 2,3-butylene oxide, styreneoxide, α-olefin oxides having 5 to 10 or more carbon atoms,epichlorohydrin, and (block- or random-added) combinations of two ormore thereof.

The specific examples of the dicarboxylic acid or the ester-formablederivative thereof in the above-described (i) include aliphaticdicarboxylic acids having 4 to 15 carbon atoms [such as succinic acid,adipic acid, sebacic acid, glutaric acid, azelaic acid, maleic acid, andfumaric acid], aromatic dicarboxylic acids having 8 to 12 carbon atoms[such as terephthalic acid, and isophthalic acid], ester-formablederivatives thereof [such as acid anhydrides (such as phthalicanhydride, and maleic anhydride), lower alky esters (such as dimethylesters, and diethyl esters), and acid halides (such as acid chloride)],and mixtures of two or more thereof.

Examples of the lactone monomer in above-described (ii) include lactoneshaving 4 to 12 carbon atoms, for example, γ-butyrolactone,γ-valerolactone, ε-caprolactone, and mixtures of two or more thereof.

Examples of the polyether diols include polyether diols each yielded bysubjecting a compound having two hydroxyl groups (for example, theaforementioned low molecular weight diols, and dihydric phenols) todehydration reaction, and compounds each having a structure in which analkylene oxide is added to a compound having two hydroxyl groups.

Examples of the dihydric phenols include bisphenols [such as bisphenolA, bisphenol F, and bisphenol S], and monocyclic phenols [such ascatechol, and hydroquinone].

Of these examples, preferred are polytetramethylene glycol, and aproduct obtained by adding an alkylene oxide to dihydric phenol. Morepreferred is a product obtained by adding EO to dihydric phenol.

Examples of the polyetherester diols include products each yielded byusing the above-described polyether diol instead of the low molecularweight diol that is a raw material in the aforementioned polyester diol,for example, products each yielded by condensation polymerization of oneor more of the above-described polyether diols, and one or more of thedicarboxylic acids or the ester-formable derivatives thereof exemplifiedas the raw material of the aforementioned polyester diols.

Of these examples of the high molecular weight diol (a3), preferred arepolyester diols, and more preferred are polycondensates each including alow molecular weight diol and a dicarboxylic acid.

As the low molecular weight diol (a4), which is optionally used togetherwith the (a2) and the (a3), the low molecular weight diols exemplifiedas the starting materials of the aforementioned polyester diols maybeused. Of these examples of the (a4), preferred are aliphatic diols. Theuse amount of the (a4) is usually 20% or less by weight, and preferably10% or less by weight based on the weight of the (a3).

The reaction temperature when the isocyanate group-terminated urethaneprepolymer (a) is produced may be the same temperature as usuallyadopted for urethanization. When a solvent is used, the temperature isusually from 20 to 100° C. When no solvent is used, the temperature isusually from 20 to 220° C., and preferably from 80 to 200° C.

In the above-described prepolymerization reaction, a catalyst usedordinarily for polyurethane may be optionally used to promote thereaction. Examples of the catalyst include amine-based catalysts [suchas triethylamine, N-ethylmorpholine, and triethylenediamine], andtin-based catalysts [such as trimethyltin laurate, dibutyltin dilaurate,and dibutyltin malate].

When the (a) is produced, the (a1) is used so as to give an excessivemole of isocyanate groups for the total mole number of the terminalhydroxide groups of the (a2), (a3) and (a4), whereby the producedcompound can be rendered an isocyanate group-terminated compound.

In the alicyclic diamine and/or aliphatic diamine (b) used for thereaction with the (a), examples of the alicyclic diamine includealicyclic diamines having 6 to 18 carbon atoms [such as4,4′-diamino-3,3′-dimehyldicyclohexylmethane,4,4′-diaminodicyclohexylmethane, diaminocyclohexane, andisophoronediamine]; and examples of the aliphatic diamine includealiphatic diamines having 2 to 12 carbon atoms [such as ethylenediamine,propylenediamine, and hexamethylenediamine]; and aromatic aliphaticdiamines having 8 to 15 carbon atoms [such as xylylenediamine, andα,α,α′,α′-tetramethylxylylenediamine]. The above-described compounds maybe used alone or in the form of a mixture of two or more thereof. Ofthese examples, preferred are isophoronediamine, andhexamethylenediamine.

The urethane resin particles (C) of the present invention for slushmolding contain, as essential components, the urethane resin (D) and theadditive (N). The additive (N) is classified into an additive (N1) to beadded before the urethane resin (D) is made into the form of particles,and an additive (N2) to be added after the urethane resin (D) is madeinto the form of particles to yield urethane resin particles (P). Theadditive (N) is used as the additive (N1) or the additive (N2).

Examples of the additive (N1) include an inorganic filler, pigmentparticles (E), a plasticizer, a releasing agent, an organic filler, astabilizer, and a dispersing agent. Examples of the additive (N2)include a pigment, a plasticizer, a releasing agent, an organic filler,a blocking inhibitor, a stabilizer, and a dispersing agent.

The addition amount (% by weight) of the additive (N) is preferably from0.01 to 50% by weight, and more preferably from 1 to 30% by weight basedon the weight of the (D).

Examples of the inorganic filler include kaolin, talc, silica, titaniumoxide, calcium carbonate, bentonite, mica, sericite, glass flake, glassfiber, graphite, magnesium hydroxide, aluminum hydroxide, antimonytrioxide, barium sulfate, zinc borate, alumina, magnesia, wollastonite,xonotlite, whisker, and a metal powder.

Of these examples, preferred are kaolin, talc, silica, titanium oxide,and calcium carbonate, and more preferred are kaolin, and talc from theviewpoint of the promotion of the crystallization of the thermoplasticresin.

The volume-average particle diameter (μm) of the inorganic filler ispreferably from 0.1 to 30, more preferably from 1 to 20, andparticularly preferably from 5 to 10 from the viewpoint of thedispersibility thereof in the thermoplastic resin.

The pigment particles (E) are not particularly limited, and knownorganic pigments and/or inorganic pigments maybe used. The particles (E)are incorporated usually in an amount of 10 parts by weight or less, andpreferably from 0.01 to 5 parts by weight per 100 parts by weight of the(C).

Examples of the organic pigment include insoluble or soluble azopigments, copper phthalocyanine-based pigments, and quinacridone-basedpigments.

Examples of the inorganic pigments include chromates, ferrocyanecompounds, metal oxides (such as titanium oxide, iron oxide, zinc oxide,and aluminum oxide), metal salts [such as sulfates (such as bariumsulfate), silicates (such as calcium silicate, and magnesium silicate),carbonates (such as calcium carbonate, and magnesium carbonate), andphosphates (such as calcium phosphate, and magnesium phosphate)], metalpowders (such as aluminum powders, iron powders, nickel powders, andcopper powders), and carbon black.

The average particle diameter of the pigment particles (E) is notparticularly limited, and is usually from 0.05 to 5.0 μm, and preferablyfrom 0.2 to 1 μm.

Examples of the plasticizer include phthalic acid esters (such asdibutyl phthalate, dioctyl phthalate, dibutylbenzyl phthalate, anddiisodecyl phthalate); aliphatic dibasic acid esters (such asdi-2-ethylhexyl adipate, and 2-ethylhexyl sebacate), trimellitic acidesters (such as tri-2-ethylhexyl trimellitate, and trioctyltrimellitate); aliphatic acid esters (such as butyl oleate); benzoicacid esters [such as a dibenzoic acid ester of polyethylene glycol(polymerization degree: 2 to 10), and a dibenzoic acid ester ofpolypropylene glycol (polymerization degree: 2 to 10)]; aliphaticphosphoric acid esters (such as trimethyl phosphate, triethyl phosphate,tributyl phosphate, tri-2-ethylhexyl phosphate, and tributoxyphosphate); aromatic phosphoric acid esters (such as triphenylphosphate, tricresyl phosphate, trixylenyl phosphate, cresyldiphenylphosphate, xylenyldiphenyl phosphate, 2-ethylhexyldiphenyl phosphate,and tris(2,6-dimethylphenyl)phosphate); halogenated aliphatic phosphoricacid esters (such as tris(chloroethyl)phosphate,tris((3-chloropropyl)phosphate, tris(dichloropropyl)phosphate, andtris(tribromoneopentyl) phosphate); and mixtures of two or more thereof.

The releasing agent may be a known releasing agent. Examples thereofinclude fluorine compound type releasing agents (such astriperfluoroalkyl (the number of carbon atoms: 8 to 20) phosphates, forexample, triperfluorooctyl phosphate, and triperfluorododecylphosphate); silicone compound type releasing agents (such asdimethylpolysiloxane, amino-modified dimethylpolysiloxane, andcarboxyl-modified dimethylpolysiloxane); aliphatic acid ester typereleasing agents (such as monohydric or polyhydric alcohol esters ofaliphatic acid having 10 to 24 carbon atoms, for example, butylstearate, hardened castor oil, and ethylene glycol monostearate);aliphatic acid amide type releasing agents (such as mono or bisamides ofaliphatic acid having 8 to 24 carbon atoms, for example, oleic amide,palmitic amide, stearic amide, and distearic amide of ethylenediamine);metal soaps (such as magnesium stearate, and zinc stearate); natural orsynthetic waxes (such as paraffin wax, microcrystalline wax,polyethylene wax, and polypropylene wax); and mixtures of two or morethereof.

The blocking inhibitor is not particularly limited, and may be knowninorganic blocking inhibitors, organic blocking inhibitors, and otherblocking inhibitors.

Examples of the inorganic blocking inhibitors include silica, talc,titanium oxide, and calcium carbonate.

Examples of the organic blocking inhibitors include thermosetting resins(such as thermosetting polyurethane resins, guanamine-based resins, andepoxy resins) having a particle diameter of 10 μm or less, andthermoplastic resins (such as thermoplastic polyurethane urea resins,and poly(meth)acrylic resins) having a particle diameter of 10 μm orless.

The stabilizer maybe a compound having, in the molecule thereof, acarbon-carbon double bond (an ethylene bond that may have a substituent)(provided that a double bond in an aromatic ring is excluded), acarbon-carbon triple bond (an acetylene bond that may have asubstituent) or other compounds. Examples thereof include esters eachincluding (meth)acrylic acid and a polyhydric alcohol (a polyhydricalcohol of a dihydric to decahydric alcohol; the same shall applyhereinafter) (such as ethylene glycol di(meth)acrylate,trimethylolpropane tri(meth)acrylate, pentaerythritoltetra(meth)acrylate, and dipentaerythritol tri(meth)acrylate); esterseach including (meth)allyl alcohol, and a polycarboxylic acid of adivalent to hexavalent carboxylic acid (such as diallyl phthalate, andtriallyl trimellitate); poly(meth)allyl ethers of a polyhydric alcohol(such as pentaerythritol(meth)allyl ether); polyvinyl ethers of apolyhydric alcohol (such as ethylene glycol divinyl ether); polypropenylethers of a polyhydric alcohol (such as ethylene glycol dipropenylether); polyvinylbenzene (such as divinylbenzene); and mixtures of twoor more thereof.

Of these examples, preferred are esters each including (meth)acrylicacid and a polyhydric alcohol, and more preferred are trimethylolpropanetri(meth)acrylate, pentaerythritol tetra(meth)acrylate, anddipentaerythritol penta(meth)acrylate from the viewpoint of stability(radical polymerization rate).

A mixing apparatus used when the additive (N2) is added to the urethaneresin particles (P) and these components are mixed with each other maybe a known powder mixing apparatus. Examples thereof includecontainer-rotating type mixers, fixed-container type mixers, andfluid-moving type mixers. Of these mixing apparatuses, fixed-containertype mixers are preferred. More preferred are high-speed flowing typemixers, biaxial paddle type mixers, high-speed shearing mixingapparatuses (such as a Henschel Mixer (registered trademark)), low-speedmixing apparatuses (such as a planetary mixer), and cone-shaped screwmixers (such as a Nauta Mixer (registered trademark)), and even morepreferred are biaxial paddle type mixers, low-speed mixing apparatuses(such as a planetary mixer), and cone-shaped screw mixers (such as aNauta Mixer (registered trademark; this note is omitted hereinafter)).The mixing is preferably attained by dry blending.

The urethane resin particles (C) of the present invention for slushmolding are preferably granulated particles. Examples of the process forproducing the urethane resin particles (C) include processes describedbelow.

[Process (1) for Producing Urethane Resin Particles (C)]

A mixture (J) of an isocyanate group-terminated urethane prepolymer (a),and a diketimine compound (b1) of an alicyclic diamine and/or analiphatic diamine (b) is mixed with a mixture (M) of an organic solvent(K) having a dielectric constant of 5 to 25, and an aqueous solution (L)containing water or a surfactant, the solvent (K) being contained in aproportion of 5 to 30% by weight of the solution (L); and then the mixedcomponents are stirred to conduct polymerization reaction to yieldurethane resin particles (P).

The process (1) is a production process in which in any step foryielding the particles (P), or after the particles (P) are yielded, anadditive (N) is incorporated into the (P), thereby yielding the urethaneresin particles (C).

The aqueous solution (L) containing water or a surfactant is preferablyan aqueous solution containing a surfactant. The same shall apply to thefollowing production processes (2) to (3).

Specifically, operations for steps (I) to (III) described below aremade, thereby yielding the urethane resin particles (C), which haveirregular particle surfaces. The particles (C) are characterized in thatthe particle diameter distribution thereof is sharp.

Step (I): an alicyclic diamine and/or an aliphatic diamine (b) are/isconverted to a diketimine compound (b1), and then a mixture (J) of aurethane prepolymer (a) and the diketimine compound (b1) is produced.

Step (II): produced is a mixture (M) of an aqueous solution (L)containing water or a surfactant, and an organic solvent (K) having adielectric constant of 5 to 25. The (K) is incorporated in a proportionof 5 to 30% by weight of the (L).

Step (III): the mixture (J) and the mixture (M) are mixed with eachother, and the mixed components are stirred to conduct polymerizationreaction to yield particles (P).

About the step (I):

The diketimine compound (b1) is a reaction compound of the alicyclicdiamine and/or aliphatic diamine (b), and a ketone compound. Examples ofthe ketone compound include aliphatic or alicyclic ketone compoundshaving 3 to 9 carbon atoms (such as acetone, methyl ethyl ketone, methylisobutyl ketone, and cyclohexanone). Of these examples, preferred areacetone and methyl ethyl ketone.

The method for synthesizing the diketimine compound (b1) is notparticularly limited, and may be a known method. Examples thereofinclude a method of heating a mixture of the diamine (s) and anexcessive amount of the ketone compound, and optionally removinggenerated water.

The mixture (J) is obtained by mixing, with the above-described urethaneprepolymer (a), the diketimine compound (b1) in an amount usually from0.5 to 1.5 equivalents, and preferably from 0.7 to 1.2 equivalents perequivalent of isocyanate groups of the (a). Outside this range, theurethane resin particles (C) having good mechanical properties are notobtained.

The temperature at the mixing time is preferably from 50 to 80° C., andthe period for the stirring is preferably from 30 to 60 seconds.

About the step (II):

Examples of the surfactant used in the aqueous solution (L) containing asurfactant include water-soluble polymers (such as methylcellulose,polyvinyl alcohol, polyethylene glycol, polyacrylic acid salts,polyvinyl pyrrolidone, and Na salts of a copolymer of diisobutylene andmaleic acid), inorganic powders (such as a calcium carbonate powder, acalcium phosphate powder, a hydroxyl apatite powder, and a silicapowder), and surfactants (such as sodium dodecylbenzenesulfonate, andsodium laurylsulfate).

The use amount of the surfactant is preferably 10% by weight or less,more preferably from 0.001 to 8% by weight, and even more preferablyfrom 0.01 to 5% by weight based on the weight of the (L). When theamount is in the above-described range, no effect is produced ontophysical properties of the resin.

The organic solvent (K) is an organic solvent having a dielectricconstant of 5 to 25. The dielectric constant is preferably from 6 to 24,and more preferably from 7 to 23. The dielectric constant 8 isrepresented by the following equation in a case where at the time offilling a sample substance into a space between electrodes of aparallel-plate capacitor having an electric capacity C0 in vacuum, theelectric capacity turns to C:ε=C/C0.

When the electric capacity that is measured not in vacuum but in the airis actually used as C0, a difference between the measured capacity andthe true C0 can be substantially ignored since the dielectric constantof the air is 1.0006.

The respective dielectric constant values of main solvents are asfollows:

-   Acetone: 21.5; methyl ethyl ketone: 15.5; tetrahydrofuran: 8.2; and    methyl acetate: 6.7.

If the organic solvent (K) has a dielectric constant of less than 5, the(K) and the aqueous solution (L) containing a surfactant are not easilymixed with each other. Thus, the particles are not granulated so thatparticles having irregular surfaces are not obtained. If the constant ismore than 25, the dielectric constant of the mixture (M) turns high.Thus, the particles are not granulated so that particles havingirregular surfaces are not obtained.

Examples of the organic solvent (K) include ketones, alcohols, ethers,and esters, and a combination of two or more thereof. The (K) ispreferably at least one selected from the group consisting of ketoneshaving 3 to 9 carbon atoms, ethers having 4 to 8 carbon atoms, andesters having 3 to 6 carbon atoms; or a combination of two or moreselected therefrom.

Examples of the ketones having 3 to 9 carbon atoms include acetone,methyl ethyl ketone (hereinafter MEK), methyl isobutyl ketone(hereinafter MIBK), and diethyl ketone.

Examples of the ethers having 4 to 8 carbon atoms includetetrahydrofuran (hereinafter THF). Examples of the esters having 3 to 6carbon atoms include methyl acetate, and ethyl acetate.

Of these examples, preferred are acetone, methyl ethyl ketone,tetrahydrofuran, and methyl acetate.

The content of the (K) in the solution (L) is from 5 to 30% by weight,preferably from 7 to 28% by weight, and even more preferably from 10 to25% by weight. If the content of the (K) is less than 5% by weight, theparticles are not granulated so that particles having irregular surfacesare not obtained. If content of the (K) is more than 30% by weight, thegranulation of the particles cannot be controlled so that particleshaving a target volume-average particle diameter are not obtained.

The temperature when the (K) and the (L) are mixed with each other ispreferably from 10 to 40° C. It is preferred that the peripheral speedis from 0.05 to 5.0 m/s, and the mixing period is from 1 to 5 minutes.The mixing is performed preferably just before the step (III).

About the step (III):

When the mixture (J) and the mixture (M) are mixed with each other andthe mixed components are stirred to conduct polymerization reaction, thestirring is performed under a condition that the peripheral speed isfrom 10 to 40 m/s, and preferably from 15 to 25 m/s. The mixing periodis preferably from 30 seconds to 5 minutes. The temperature of themixture (J) is preferably from 50 to 80° C., and that of the mixture (M)is preferably from 10 to 40° C. When the mixing conditions are in theabove-described ranges, the shear and aggregation of the particles arerepeated in the polymerization reaction to make it possible to yieldparticles having irregular surfaces and having a sharp particle diameterdistribution.

The apparatus for the granulation is not particularly limited as far asthe apparatus is an apparatus commercially available as an emulsifyingmachine or a dispersing machine. Examples thereof include batch typeemulsifying machines such as a homogenizer (manufactured by IKA), aPolytron (manufactured by Kinematica, Inc.), and a T K Auto Homomixer(manufactured by PRIMIX Corporation), continuous type emulsifyingmachines such as an Ebara Milder (manufactured by Ebara Corporation), aT K Filmix, and a T K Pipe Line Homomixer (manufactured by PRIMIXCorporation), a colloidal mill (manufactured by Shinko Pantec Co.,Ltd.), a slusher, a trigonal wet pulverizer (manufactured by MitsuiMiike Chemical Engineering Machinery, Co., Ltd.), a Capitron(manufactured by Eurotec Ltd.), and a fine flow mill (manufactured byPacific Machinery & Engineering Co., Ltd.), high-pressure emulsifyingmachines such as a Micro Fluidizer (manufactured by MIZUHO IndustrialCo., Ltd.), a Nanomizer, (manufactured by Nanomizer Inc.), and an APVGaulin (manufactured by Gaulin), membrane emulsifying machines such as amembrane emulsifying machine (manufactured by REICA Co., Ltd.),vibrating emulsifying machines such as a Vibro Mixer (manufactured byREICA Co., Ltd.), and ultrasonic emulsifying machines such as anultrasonic homogenizer (manufactured by Branson). Of these examples,preferred are an APV Gaulin, a homogenizer, a T K Auto Homomixer, anEbara Milder, a T K Filmix, and a T K Pipe Line Homomixer.

The method for the solid-liquid separation may be known centrifugalseparation, belt press, filter press or some other method. When theresultant solid is further dried by a known method, the urethane resinparticles (P) can be yielded which have surfaces having irregularities.

In any step for yielding the particles (P), or after the particles (P)are yielded, an additive (N) is incorporated into the (P), therebymaking it possible to yield the urethane resin particles (C).

The method for adding the additive (N) to the urethane resin particles(P), and mixing these substances is the same as described above.

[Process (2) for Producing Urethane Resin Particles (C)]

Through a step 1 and a step 2-1 or 2-2 that are described below,urethane resin particles (P) are yielded which have surfaces havingirregularities. The process (2) is a production process in which in anystep for yielding the particles (P), or after the particles (P) areyielded, an additive (N) is incorporated into the (P), thereby yieldingthe urethane resin particles (C). The particles (C) are characterized inthat the particle diameter distribution thereof is sharp.

Step 1:

A step of producing urethane resin fine particles (G) containing aurethane resin (D), and having a central particle diameter of 1 to 100μm.

Step 2-1:

A step of heating the urethane resin fine particles (G) to a temperatureof [the thermally softening temperature of the (D) −10] to [thethermally softening temperature of the (D) +10]° C. while the particlesare stirred at a peripheral speed of 0.5 to 50 m/s, whereby theparticles are granulated; and then cooling the particles after it isverified that the central particle diameter of the resultant particlesreaches a predetermined particle diameter, whereby the resultantparticles are granulated into the urethane resin particles (P).

Step 2-2:

A step of heating the (G) to a temperature of 70 to [the thermallysoftening temperature of the (D) +10]° C. in the presence of an organicsolvent (T), the difference between the solubility parameter (SP value)of the (T) and that of the urethane resin (D) being 3 or less, and theamount of the (T) being from 5 to 30% by weight based on the weight ofthe (G), while the particles (G) are stirred at a peripheral speed of0.5 to 50 m/s, whereby the particles (G) are granulated; and thencooling the resultant particles after it is verified that the centralparticle diameter of the resultant particles reaches a predeterminedparticle diameter, whereby the resultant particles are granulated intothe urethane resin particles (P).

About the step 1:

The urethane resin fine particles (G) have a central particle diameterof 1 to 100 μm, preferably 5 to 70 μm, and even more preferably 10 to 50μm.

If a raw material fine powder having a central particle diameter morethan 100 μm is used, the particle diameter distribution of the producedthermoplastic polyurethane resin powder becomes wide so that the powderis poor in powder fluidity. The use of a raw material having a centralparticle diameter less than 1 μm is unsuitable from the viewpoints ofthe powder fluidity and the scattering of the powder in the production,and other viewpoints.

The urethane resin fine particles (G) are yielded, for example, bycausing an isocyanate group-terminated urethane prepolymer (a) to reactwith a diketimine compound (b1) of an alicyclic diamine and/or analiphatic diamine (b) in an aqueous solution (L) containing water or asurfactant. Specifically, those described in, for examplesJP-A-H8-120041 and others, may be used.

The central particle diameter of the (G) can be controlled into a sizeof 1 to 100 μm in accordance with the amount of the dispersing agent,the rotation number of the dispersing machine, or some other factor.

The thermally softening temperature of the urethane resin (D) is notparticularly limited, and is preferably from 100 to 200° C., and morepreferably from 120 to 180° C. When the thermally softening temperatureis set into the above-described range, a thermoplastic polyurethaneresin powder can be yielded which is excellent in heat resistance, andthermal meltability.

About the step 2-1:

In the granulating temperature, the particles are heated preferably to atemperature of [the thermally softening temperature of the (D) −10] to[the thermally softening temperature of the (D) +10]° C., and morepreferably a temperature of [the thermally softening temperature of the(D) −5] to [the thermally softening temperature of the (D) +5]° C.

At the time of the granulation, the stirring is performed such that theperipheral speed is from 0.5 to 50 m/s, and preferably from 8 to 40 m/s.If the peripheral speed is less than 0.5 m/s, the cohesive force betweenthe particles is far larger than the shearing force so that theparticles become coarse. If the peripheral speed is more than 50 m/s,the shearing force is very strong so that at the granulation time theparticle diameter cannot be controlled. The peripheral speed ispreferably from 8 to 40 m/s since heat can be evenly given to thepowder.

When the peripheral speed is 8 m/s or more, the particles generate heatresulting from frictional heat based on the shearing. When this heat isused to heat the powder to be granulated, deposits on the jacket can bemade extremely lower in quantity than when the particles are granulatedonly by heating the jacket.

The granulating machine is not particularly limited, and preferably anapparatus good in stirring efficiency. Examples thereof includehigh-speed shearing mixing apparatuses [such as a “Henschel Mixer”manufactured by Nippon Coke & Engineering Co., Ltd., and a “High SpeedMixer” manufactured by Fukae Industries Co., Ltd.], and low-speed mixingapparatuses [such as a planetary mixer manufactured by Asada Iron WorksCo., Ltd., and a Nauta Mixer manufactured by Hosokawa Micron Group].

The end point of the granulation is decided to a point where the centralparticle diameter of the urethane resin particles (P) that is obtainedwhile the central particle diameter is measured becomes a predetermineddesired particle diameter.

The predetermined desired particle diameter may be preferably selectedfrom the range of 10 to 500 μm. When the granulation has reached the endpoint, the urethane resin particles (P) are immediately cooled to 50° C.or lower so as not to advance further granulation. The central particlediameter is measured through a laser diffraction type particle diameterdistribution measuring apparatus.

About the step 2-2:

The method for adding the organic solvent (T) is not particularlylimited. Thus, the total volume of the (T) may be charged at a time intothe urethane resin fine particles (G) before the particles (G) aregranulated, or the (T) may be intermittently charged thereinto.

The method for the charging is preferably the dropping or spraying ofthe solvent while the particles are stirred. The spraying is preferredfrom the viewpoint of evenness.

In the organic solvent (T), the difference between the solubilityparameter (SP value) thereof and that of the urethane resin (D) is 3 orless, and preferably 1 or less. If the difference between the SP valueof the (D) and that of the (T) is more than 3, the granulation is notattained.

The SP value is calculated by the Fedors method.

The SP value is represented by the following equation:SP value(δ)=(ΔH/V)^(1/2)wherein ΔH represents the molar evaporation heat (cal/mol), and Vrepresents the molar volume (cm³/mol).

For ΔH, and V, the following may be used: the total (ΔH) of therespective molar evaporation heats of atomic groups, and the total (V)of the respective molar volumes thereof described in “POLYMERENGINEERING AND SCIENCE FEBRUARY, 1974, Vol. 14, No. 2, ROBERT F. FEDORS(pp. 151-153) ”, and “POLYMER ENGINEERING AND SCIENCE JUNE, 1974, Vol.14, No. 6, ROBERT F. FEDORS (p. 472)”.

The SP value is an index for representing the following: substances nearto each other in this value are easily mixed with each other (highcompatibility) ; and substances apart from each other in this value arenot easily mixed with each other.

The solubility parameter of the urethane resin (D) is preferably from 8to 12.

Examples of the organic solvent (T) having a difference of 3 or lessbetween the SP value of the solvent and that of the (D) include ketones,alcohols, ethers, and a combination of two or more thereof. Preferredare at least one selected from the group consisting of ketones having 3to 9 carbon atoms, and ethers having 4 to 8 carbon atoms; and acombination of two or more selected therefrom.

Examples of the ketones having 3 to 9 carbon atoms include acetone,methyl ethyl ketone (hereinafter MEK), methyl isobutyl ketone(hereinafter MIBK), and diethyl ketone. Examples of the ethers having 4to 8 carbon atoms include tetrahydrofuran (hereinafter THF). Preferredare acetone, methyl ethyl ketone, methyl isobutyl ketone, andtetrahydrofuran.

The addition amount of the organic solvent (T) is from 5 to 30% byweight, and preferably from 10 to 25% by weight of the urethane resinfine particles (G). If the addition amount is less than 5% by weight,the bonding strength between the particles is weak so that thegranulation is not attained. If the addition amount is more than 30% byweight, the particles turn into a pasty form. Thus at the time of thegranulation, coarse particles are generated so that the particlediameter distribution becomes wide.

When the organic solvent (T) is sprayed, the granulation can be attainedat a lower temperature as compared with when the (T) is not sprayed. Theparticles are heated such that the granulation temperature is preferablya temperature of 70 to [the thermally softening temperature of the (D)+10]° C., and more preferably a temperature of 80 to [the thermallysoftening temperature of the (D) +5]° C.

The stirring at the granulation time is performed at a peripheral speedof 0.5 to 50 m/s, and preferably 5 to 40 m/s. If the peripheral speed isless than 0.5 m/s, the cohesive force between the particles is farlarger than the shearing force so that the particles become coarse. Ifthe peripheral speed is more than 50 m/s, the shearing force is verystrong so that at the granulation time the particle diameter cannot becontrolled.

The granulating machine is the same as used in the step 2-1.

The end point of the granulation may be performed in the same way as inthe step 2-1.

The method for removing the remaining portion of the organic solvent (T)after the granulation maybe a known method (such as de-solvation).

The removing method is, for example, a method of heating the systemwhile the inside thereof is stirred under reduced pressure or normalpressure, thereby removing the solvent. However, if the system is heatedto a temperature of 70° C. or higher, the resultant is furthergranulated. Thus, it is essential that the heating temperature is 70° C.or lower.

The urethane resin particles (P) yielded in this process arecharacterized in that the particles (P) have a particle diameterdistribution Cv of 20 to 55 (the ratio of the 90% particle diameter tothe 10% particle diameter is from 2.0 to 3.0), and the particle diameterdistribution is sharp in a wide particle diameter range.

The central particle diameter d of the (P) is preferably from 20 to 500μm since the particle diameter distribution Cv is easily controlled.

The central particle diameter d, and the particle diameter distributionCv referred to herein maybe measured by means of a laser diffractiontype particle diameter distribution measuring apparatus, or some otherapparatus. In a relative cumulative particle diameter distribution curveobtained in this manner, d corresponds to the particle diameter d50obtained when the cumulative quantity is 50%, and Cv is defined asrepresented by the following equation, using the standard deviation SDand d50:Cv=SD/d50

In any step for yielding the particles (P), or after the particles (P)are yielded, an additive (N) is incorporated into the (P), therebyyielding the urethane resin particles (C).

The method for adding the additive (N) to the urethane resin particles(P), and mixing these substances is the same as described above.

[Process (3) for Producing Urethane Resin Particles (C)]

Through steps 3 and 4 described below, urethane resin particles (P) areyielded which have surfaces having irregularities. The process (3) is aproduction process in which in any step for yielding the particles (P),or after the particles (P) are yielded, an additive (N) is incorporatedinto the (P), thereby yielding the urethane resin particles (C). Theparticles (C) are characterized in that the particle diameterdistribution thereof is sharp.

Step 3:

A step of producing urethane resin fine particles (G) containingurethane resin (D), and having a central particle diameter of 1 to 100μm; and subsequently producing a slurry (R) which contains the (G) andan aqueous solution (L) containing water or a surfactant.

Step 4:

A step of adding, to the slurry (R), an organic solvent (T), thedifference between the solubility parameter (SP value) of the (T) andthat of the urethane resin (D) being 3 or less; and then stirring theresultant mixture at a temperature of 10 to [the boiling point of theorganic solvent (T)]° C. and a peripheral speed of 0.1 to 10 m/s,whereby the urethane resin fine particles (G) are granulated into theurethane resin particles (P).

About the step (3):

The production of the urethane resin fine particles (G) is the same asin the aforementioned production process (2).

The urethane resin fine particles (G) are dispersed in the aqueoussolution (L) containing water or a surfactant to prepare a slurry. Theaqueous solution (L) containing water or a surfactant is the same as inthe aforementioned production process (1).

The urethane resin fine particles (G) are added to the (L) preferably ina proportion of 15 to 50% by weight, and more preferably 20 to 40% byweight. When the proportion is in the above-described range, thefrequency of collision between the particles is high so that theparticles can be mixed with each other evenly. Thus, a target particlediameter can be obtained.

The method for preparing the slurry is preferably a method of chargingthe urethane resin fine particles (G) into the (L) without causing the(G) to aggregate with each other.

The temperature for preparing the slurry is preferably from 5 to 40° C.The mixture is stirred preferably under a condition that the peripheralspeed is from 0.1 to 10 m/s.

About the step (4):

After the above-mentioned step for preparing the slurry, an organicsolvent (T) is added to the slurry (R). In the organic solvent (T), thedifference between the solubility parameter (SP value) thereof and thatof the urethane resin (D) is 3 or less, preferably 1 or less. If thedifference between the SP value of the (D) and that of the (T) is morethan 3, the granulation is not attained.

The organic solvent (T) is the same as in the aforementioned productionprocess (2).

The addition amount of the organic solvent (T) to the above-describedslurry (R) is preferably from 2 to 50% by weight, and more preferablyfrom 5 to 30% by weight. When the amount is from 2 to 50% by weight, thebonding strength between the particles is strong and further theparticle diameter distribution is also narrow.

The method for adding the organic solvent (T) is not particularlylimited, and the (T) maybe charged into the slurry (R) at a time orintermittently. In the middle of the granulation, the solvent may bedropwise added thereto.

When the organic solvent (T) is added to the slurry (R) and the mixtureis stirred, the urethane resin fine particles (G) can be granulated intothe urethane resin particles (P).

At the granulation, the mixture is stirred at a peripheral speed of 0.1to 10 m/s, and preferably 0.5 to 5 m/s. If the peripheral speed is lessthan 0.1 m/s, the cohesive force between the particles is far largerthan the shearing force so that the particles become coarse. If theperipheral speed is more than 10 m/s, the shearing force is very strongso that the particles do not aggregate with each other. Thus, thegranulation cannot be attained.

The stirring blades are not particularly limited, and are preferablyblades good in stirring efficiency. Examples thereof include paddleblades, ribbon blades, spiral blades, and anchor-shaped blades.

The granulation temperature is from 10 to [the boiling point of theorganic solvent (T)]° C., and preferably from 50 to [the boiling pointof the organic solvent (T) −10]° C.

If the granulation temperature is lower than 10° C., the particles arenot combined with each other so that the granulation cannot be attained.If the temperature is higher than the boiling temperature of the organicsolvent (T), the organic solvent (T) vaporizes so that a target particlesize and a target particle size distribution cannot be obtained.

The end point of the granulation is decided to a point where the centralparticle diameter of the urethane resin particles (P) that is obtainedwhile the particle diameter is measured reaches a desired particlediameter in the range of 20 to 500 μm.

The method for the solid-liquid separation, and the method for thedrying are the same as in the process (1) for producing the urethaneresin particles (C).

The urethane resin particles (P) yielded through this process arecharacterized in that the particles (P) have a central particle diameterof 20 to 500 μm, and a particle diameter distribution Cv of 20 to 55(the ratio of the 90% particle diameter to the 10% particle diameter isfrom 2.0 to 3.0), and the particle diameter distribution is sharp in awide particle diameter range.

The present production process does not make it possible to produceurethane resin particles (P) having a particle diameter distribution Cvof less than 20. If the Cv is over 55, generated are fine particleshaving sizes of several micrometers and coarse particles having sizes ofseveral hundreds of micrometers. It is therefore necessary to classifythe particles.

In any step for yielding the particles (P), or after the particles (P)are yielded, an additive (N) is incorporated into the (P), therebymaking it possible to yield the urethane resin particles (C).

The method for adding the additive (N) to the urethane resin particles(P), and mixing these substances is the same as described above.

[Method for Coloring Urethane Resin Particles (C)]

The urethane resin particles (C) can furthest produce advantageouseffects thereof when the additive (N) contains at least pigmentparticles (E) so that the particles (C) are colored.

In other words, for the urethane resin particles (C) comprising theurethane resin particles (P) and the pigment particles (E), theparticles (P) are mixed with and the (E), thereby making it possible toyield the urethane resin particles (C) for slush molding in which theparticles (E) adhere to the surfaces of the particles (P).

In the urethane resin particles (C), almost all of the mixed particles(E) adhere onto the surfaces of the particles (P), in particular,depressions therein so that aggregations of the pigment particles arehardly generated. Thus, the particles (C) are characterized in that aparticle (F) is contained in a number of one or less per one hundred ofthe urethane resin particles (P), the particle (F) being a particle thathas a particle diameter of 20 to 140 μm and is an aggregate of thepigment particles (E).

For the urethane resin particles (C) of the present invention, it isdesired that the particle (F) is contained in a number of one or lessper one hundred of the urethane resin particles (P), the particle (F)being a particle that has a particle diameter of 20 to 140 μm and is anaggregate of the pigment particles (E).

Examples of the particle (F) include not only particles produced by theaforementioned pigment particles (E) slipped down from the surfaces ofthe urethane resin particles (C) and then aggregated with each other,but also particles that are the pigment particles (E) which have alreadyaggregated before mixed with the urethane resin particles (P), that is,at the time when the pigment particles (E) are in the form of a coloringagent paste, a pigment powder or some other. When the particle (F) iscontained in a number of one or less per one hundred of the urethaneresin particles (P), the color of the pigment is well developed. Thus,the use amount of the pigment is favorably sufficient to be small formaking vivid the developed color of the urethane resin particles (C), orthe color of a body obtained by melt-molding the particles (C).

When the additive (N) is pigment-dispersed resin particles (SE) in whichthe pigment particles (E) are dispersed in a resin (S), for the urethaneresin particles (C) comprising the urethane resin particles (P) and thepigment-dispersed resin particles (SE), the particles (P) are mixed withthe (SE), thereby making it possible to yield the urethane resinparticles (C) for slush molding in which the particles (SE) adhere ontothe surfaces of the particles (P).

By adding, to such particles having irregular surfaces,pigment-dispersed resin particles in which a pigment is dispersed in aresin in a high concentration, the resin particles where the dispersionstate is kept can be fixed into depressions in the surfaces. Thus, theparticles can be colored without causing the pigment to slip down oraggregate.

Examples of the resin (S) include a vinyl resin, an epoxy resin, apolyester resin, a polyamide resin, a polyurethane resin, a polyimideresin, a silicon-based resin, a phenolic resin, a melamine resin, a urearesin, an aniline resin, an ionomer resin, and a polycarbonate resin;and alloys, blend resins, block copolymers, or graft polymers eachobtained by mixing two or more of these resins with each other. Of theseexamples, preferred are a urethane resin and alloys or blend resins eachincluding a urethane resin and some other resin from the viewpoint ofcompatibility.

Examples of the method for dispersing the pigment (E) into the resin (S)include, but are not particularly limited to, methods of mixing anddispersing of the pigment (E) by use of a three-roll mill, a Banburymixer, a biaxial extruder, a kneader or some other. The temperature atthe time of the dispersing is usually from 100 to 180° C., and thedispersing period is usually from 1 minute to 1 hour. Alternatively,there is a method of dispersing the pigment (E) into a monomer for theresin, which is at a stage before polymerization, and then polymerizingthe monomer into a high molecular weight, thereby yielding apigment-dispersed resin in which the pigment particles (E) are dispersedin the resin (S). There is a method of using a jet mill pulverizer orsome other to pulverize the pigment-dispersed resin in which theparticles (E) have been dispersed by these methods, thereby yielding thepigment-dispersed resin particles (SE).

Further, there is exemplified a method of dispersing a pigment into amonomer for the resin, which is at a stage before polymerization,emulsifying or dispersing this dispersion system into water, or anorganic solvent in which the monomer is insoluble, and subsequentlypolymerizing this monomer, thereby yielding the pigment-dispersed resinparticles (SE).

The concentration of the (E) in the (SE) is preferably from 20 to 90% byweight, more preferably from 30 to 80% by weight, and most preferablyfrom 40 to 60% by weight. The ratio of the particle diameter of theresin particles (P) to that of the pigment-dispersed resin particles(SE) is preferably from 100:0.5 to 100:50, more preferably from 100:1 to100:10, and most preferably from 100:1.5 to 100:5.

When the additive (N) is a pigment-dispersed liquid (HE) in which thepigment particles (E) are dispersed in an organic compound (H) having amelting point of 0° C. or lower and a boiling point of 170° C. orhigher, and containing in the molecule thereof at least one ester group,for the urethane resin particles (C) comprising the urethane resinparticles (P) and the pigment-dispersed liquid (HE), the particles (P)are mixed with the (HE), thereby making it possible to yield theurethane resin particles (C) for slush molding in which the (HE) adheresonto the surfaces of the particles (P).

When this method is performed, the urethane resin particles (C) can beefficiently colored with good reproducibility of the color.

The organic compound (H) is good in property of dispersing the pigmentparticles (E); thus, the pigment-dispersed liquid (HE) can be storedover a long term without generating the aggregation of the pigment.Moreover, the pigment-dispersed liquid (HE) comprising the organiccompound (H) and the pigment particles (E) is high in affinity with theurethane resin particles (P); thus, the surfaces of the particles can becolored evenly in a shorter period in this case than in a case where theurethane resin particles (P) are colored with only the pigment particles(E).

Examples of the organic compound (H) include the same as given as theexamples of the aforementioned plasticizer.

Of these examples, preferred are benzoic acid esters, and particularlypreferred are dibenzoic acid esters of polyethylene glycol.

The urethane resin particles (C) of the present invention for slushmolding may be subjected to slush molding, thereby yielding a resinmolded body. For the slush molding, use may be made of a method ofvibrating/rotating a box in which the urethane resin particles (C) ofthe present invention are put, and a heated mold together, to melt andfluidize the urethane resin particles (C) inside the mold, and thencooling/solidifying the fluidized particles to produce a molded body(such as a skin body).

The temperature (° C.) of the mold is preferably from 200 to 280° C.

The resin molded body, which is yielded by the slush molding of theurethane resin particles (C) of the present invention, is suitable forinterior materials (such as an instrument panel, and a door trim) of anautomobile.

For example, the resin molded body (skin body) molded from the urethaneresin particles (C) of the present invention preferably has a thicknessof 0.3 to 1.2 mm. The molded body (skin body) can be rendered a resinmolded product by setting the body to a foaming mold to bring the frontsurface of the body into contact with the mold, and then causing aurethane foam to flow thereinto, thereby forming a foamed layer having athickness of 5 to 15 mm onto the rear surface.

In the case of smooth surfaces, which have no irregularities, a particle(F), which is an aggregate of the pigment particles (E), is remarkablygenerated. However, the urethane resin particles (C) of the presentinvention have irregular particle surfaces; thus, it does not occur thatthe pigment particles adhering onto the resin particle surfaces areslipped down from the surfaces or the pigment particles are aggregatedwith each other on the particle surfaces by shear generated at thestirring and mixing time in the coloring step, or a step subsequentthereto. As a result, the urethane resin particles (C) are good incolor-developability. Furthermore, there are not caused a problem thatthe particles (F), which are aggregates of the pigment, are intermingledwith the final product, or other problems.

Moreover, when the process of the present invention is compared with aprocess in which a pigment is mixed with a liquid raw material ofparticles, which is at a stage before the raw material is made into theparticles, the present invention does not require any step of washingfacilities for the production carefully whenever the product color ischanged. Thus, the present invention can make an improvement inproduction performance.

EXAMPLES

Hereinafter, the present invention will be more specifically describedby way of examples. However, the present invention is not limitedthereto. In the following description, “part(s)” and “%” represent“part(s) by weight” and “% by weight”, respectively.

Production Example 1

Production of Prepolymer Solution (U-1):

Into a reaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube were charged polybutylene adipate (575 parts)having a number-average molecular weight (hereinafter described as Mn)of 1000, polyhexamethylene isophthalate (383 parts) having an Mn of 900,1-octanol (16.8 parts), and kaolin (18.6 parts) having a volume-averageparticle diameter of 9.2 μm, and then the inside of the vessel waspurged with nitrogen. Thereafter, while stirred, the mixture was heatedto 110° C. to be melted. The mixture was then cooled to 60° C.Subsequently, thereinto was charged hexamethylene diisocyanate (242parts), and then the reactive components were caused to react at 85° C.for 6 hours. Next, the mixture was cooled to 60° C., and then theretowere added tetrahydrofuran (217 parts), a stabilizer (2.5 parts)[Irganox 1010, manufactured by Ciba Specialty Chemicals Ltd.], and anultraviolet absorber (1.91 parts) [Tinuvin 571, manufactured by CibaSpecialty Chemicals Ltd.]. The components were mixed with each otherevenly to yield a prepolymer solution. In the resultant prepolymersolution (U-1), the NCO content was 2.2%.

Production Example 2

Production of Prepolymer (U-2):

Into a reaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube were charged polybutylene adipate (1214 parts)having an Mn of 1000, polyethylene phthalate having an Mn of 900 (ratioby weight of terephthalic acid to isophthalic acid =50/50) (304 parts),1-octanol (27.6 parts), and kaolin (18.6 parts) having a volume-averageparticle diameter of 9.2 μm, and then the inside of the vessel waspurged with nitrogen. Thereafter, while stirred, the mixture was heatedto 110° C. to be melted. The mixture was then cooled to 60° C.Subsequently, thereinto was charged hexamethylene diisocyanate (313.2parts), and then the reactive components were caused to react at 85° C.for 6 hours. Next, the system was cooled to 60° C., and then theretowere added tetrahydrofuran (425 parts), a stabilizer (2.7 parts)[Irganox 1010], and an ultraviolet absorber (1.91 parts) [Tinuvin 571,manufactured by Ciba Specialty Chemicals Ltd.]. The components weremixed with each other evenly to yield a prepolymer solution. In theresultant prepolymer solution (U-2), the NCO content was 1.6%.

Production Example 3

Production of Prepolymer (U-3):

A prepolymer (U-3) was yielded in the same way as in Production Example2 except that use was made of polyethylene terephthalate having an Mn of2500 (ratio by weight of terephthalic acid to isophthalic acid=50/50)instead of the polyethylene phthalate (terephthalic acid to isophthalicacid=50/50)having an Mn of 900. In the resultant prepolymer solution(U-3), the NCO content was 0.8%.

Production Example 4

Production of MEK Ketimine Compound of Diamine:

While hexamethylenediamine and an excessive amount of MEK (methyl ethylketone; molar quantity: 4 times the molar quantity of the diamine) wererefluxed at 80° C. for 24 hours, water generated therefrom was removedto the outside of the system. Thereafter, an unreacted portion of MEKwas removed under reduced pressure to yield an MEK ketimine compound.

Production Example 5

Production of Dispersion Medium (Y-1):

Into 980 parts of water was dissolved 20 parts of a dispersing agentcontaining a Na salt of a copolymer including diisobutylene and maleicacid [Sanspearl PS-8, manufactured by Sanyo Chemical Industries, Ltd.]as a dispersing agent, and then the temperature of the solution wasadjusted to 25° C. to yield a dispersion medium (Y-1).

Production Example 6

Production of Pigment-Dispersed Resin Particles (SE-1):

Into a reaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube were charged 300 parts of a bisphenol A-EO (2moles) adduct, 440 parts of a bisphenol A-PO (2 moles) adduct, 270 partsof terephthalic acid, and 2 parts of potassium titanyl oxalate as acondensation catalyst. The reactive components were caused to react witheach other at 230° C. in the flow of nitrogen for 10 hours while watergenerated therefrom was distilled off. Next, the reactive componentswere caused to react with each other under a reduced pressure of 5 to 20mmHg. At a time when the acid value turned to 2 or less, the system wascooled to 180° C. Thereto was added 45 parts of trimellitate anhydrideto cause the reactive components to react with each other for 2 hoursunder normal pressure in a closed environment. Thereafter, the reactionproduct was taken out. In this way, a polyester resin was yielded. Threerolls having a heating temperature of 130° C. were used to mix 100 partsof this polyester resin with 70 parts of carbon black, MA-100[manufactured by Mitsubishi Chemical Corporation]. The mixture wascooled to room temperature, and then pulverized by means of a jet millpulverizer to yield pigment-dispersed resin particles (SE-1) (content ofthe pigment particles: 41% by weight), which were a 400-mesh(sieveopening size: 38 μm)-passed product. The (SE-1) had a central particlediameter of 17 μm.

Example 1

Production of Urethane Resin Particles (P-1):

Into a reaction vessel were charged the prepolymer solution (U-1) (100parts) and the MEK ketimine compound (5.6 parts), and these componentswere mixed with each other. Thereto were added 340 parts of an aqueoussolution in which a dispersing agent (Sanspearl PS-8 (1.3 parts)manufactured by Sanyo Chemical Industries, Ltd.), and tetrahydrofuran(dielectric constant: 8.2) (68 parts) were dissolved (content of theorganic solvent in the aqueous solution: 20% by weight). An ultradisperser manufactured by Yamato Scientific Co., Ltd. was then used tomix these components at a rotation number of 9000 rpm (peripheral speed:15 m/s) for 1 minute. This mixture was shifted to a reaction vesselequipped with a thermostat, a stirrer and a nitrogen-blowing tube. Theinside of the vessel was purged with nitrogen, and then the reactivecomponents therein were caused to react with each other at 50° C. for 10hours while the mixture was stirred. After the end of the reaction, theresultant was separated by filtration, and then dried to produceurethane resin particles (P-1). The (P-1) had an Mn of 25,000, and acentral particle diameter of 151 μm.

Into a Henschel Mixer were charged 100 parts of the resultant (P-1) anda pigment-dispersed liquid (HE-1) (2.7 parts) as a coloring agent inwhich 1.0 part of carbon black was dispersed in 1.0 part of an organiccompound (H-1) which was a dibenzoic acid ester (Sansoft EB300,manufactured by Sanyo Chemical Industries, Ltd., melting point: 0° C. orlower; boiling point: 300° C. or higher) of polyethylene glycol(polymerization degree: 2 to 10). The mixture was stirred at a rotationspeed of 700 minutes⁻¹ for 1 minute. Next, the mixture was shifted to aNauta Mixer having a volume of 100 L, and thereto were chargeddipentaerythritol pentaacrylate (4.0 parts), an ultraviolet stabilizer(0.3 parts) [Tinuvin 765, manufactured by Ciba Specialty Chemicals Ltd.]to immerse the mixture in this liquid at 70° C. for 4 hours. After the4-hour immersion, thereinto were charged two kinds ofinternally-additive releasing agents {a dimethylpolysiloxane (0.06parts) [KL45-10000, manufactured by Nippon Unicar Co., Ltd.], and acarboxyl-modified silicone (0.05 parts) [X-22-3710, manufactured byShin-Etsu Chemical Co., Ltd.]}, and then these components were mixedwith each other for 1 hour. Thereafter, the mixture was cooled to roomtemperature. Finally, thereto was charged a blocking inhibitor [GanzPearl PM-0305, manufactured by Ganz Chemical Co., Ltd.] (0.5 parts), andthe components were mixed with each other. The mixture was passedthrough a sieve having a mesh of 48. From the resultant, particlespassed through a sieve having a mesh of 200 were removed to yieldurethane resin particles (C-1) for slush molding.

Example 2

Production of Urethane Resin Particles (C-2):

Urethane resin particles (P-2) were produced in the same way as inExample 1 except that instead of the tetrahydrofuran, 15 parts of sodiumchloride was added to the aqueous solution. The (P-2) had an Mn of25,000, and a central particle diameter of 180 μm.

Urethane resin particles (C-2) for slush molding were yielded in thesame way as in Example 1 except that the particles (P-2) were usedinstead of the particles (P-1) in Example 1.

Example 3

Production of Urethane Resin Particles (C-3):

While a T K Pipe Line Homomixer (manufactured by PRIMIX Corporation) wasdriven at 3600 rpm, an oil phase in which the prepolymer (U-1) (100parts) and the MEK ketimine compound (5.6 parts) were charged into areaction vessel and then these components were mixed with each other,and an aqueous solution in which a polyvinyl alcohol (manufactured byKuraray Co. , Ltd.) (5.3 parts) was dissolved as a dispersing agent weresent to the homomixer at flow rates of 100 kg/hour, and 400 kg/hour,respectively, to conduct dispersion. This mixture was shifted to areaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube, and then the inside thereof was purged withnitrogen. While the mixture was stirred, the reactive components thereinwere caused to react with each other at 50° C. for 10 hours. After thetermination of the reaction, the resultant was separated by filtration,and then dried to produce urethane fine particles (G-3). The fineparticles (G-3) had a thermally softening temperature of 140° C., and acentral particle diameter of 20 μm. The particles were put into aHenschel Mixer, and stirred at 40 m/sec. to granulate the fine particles(G-3). After 15 minutes from the start of the stirring, the temperaturereached 140° C. At this stage, the driving was stopped to yield urethaneresin particles (P-3). The (P-3) had an Mn of 25,000, and a centralparticle diameter of 180 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-3) were used, urethane resin particles (C-3)for slush molding were yielded.

Example 4

Production of Urethane Resin Particles (C-4):

Urethane fine particles (G-4) were yielded in the same way as in Example3 except that instead of the MEK ketimine compound (5.6 parts), 1-4butanediol (2.6 parts) was used. The fine particles (G-4) had athermally softening temperature of 91° C., and a central particlediameter of 3 μm.

The particles were put into a Henschel Mixer, and stirred at 40 m/sec.to granulate the fine particles (G-4). After 15 minutes from the startof the stirring, the temperature reached 90° C. At this stage, thedriving was stopped to yield urethane resin particles (P-4). The (P-4)had an Mn of 25,000, and a central particle diameter of 20 μm.

Urethane resin particles (C-4) for slush molding were yielded in thesame way as in Example 1 except that instead of the (P-1) in Example 1,the particles (P-4) were used and further the processing that “theparticles passed through a sieve having a mesh of 200 were removed” wasomitted.

Example 5

Production of Urethane Resin Particles (C-5):

Urethane resin particles (P-5) were yielded in the same way as inExample 3 except that the period for driving the Henschel Mixer waschanged to 25 minutes. The (P-5) had an Mn of 25,000, and a centralparticle diameter of 500 μm.

Urethane resin particles (C-5) for slush molding were yielded in thesame way as in Example 1 except that instead of the (P-1) in Example 1,the particles (P-5) were used and further instead of the processing that“the mixture was passed through a sieve having a mesh of 48, and fromthe resultant, particles passed through a sieve having a mesh of 200were then removed”, a processing that “the mixture was passed through asieve having a mesh of 26” was performed.

Example 6

Production of Urethane Resin Particles (C-6):

Into a reaction vessel were charged the prepolymer (U-2) (100 parts),and the MEK ketimine compound (4.1 parts), and the components were mixedwith each other. Thereto was added 340 parts of an aqueous solution inwhich a dispersing agent (Sanspearl PS-8 (1.3 parts), manufactured bySanyo Chemical Industries, Ltd.) and methyl ethyl ketone (dielectricconstant: 15.5) (68 parts) were dissolved (content of the organicsolvent in the aqueous solution: 20% by weight). An ultra disperser wasused to mix these components with each other at a rotation number of9000 rpm (peripheral speed: 15 m/s) for 1 minute. This mixture wasshifted to a reaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube, and then the inside thereof was purged withnitrogen. While the mixture was stirred, the reactive components thereinwere caused to react with each other at 50° C. for 10 hours. After thetermination of the reaction, the resultant was separated by filtration,and then dried to produce urethane resin particles (P-6). The (P-6) hadan Mn of 18,000, and a central particle diameter of 143 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-6) were used, urethane resin particles (C-6)for slush molding were yielded.

Example 7

Production of Urethane Resin Particles (C-7):

While an apparatus, DISPAX-REACTOR (manufactured by IKA), was driven at12000 rpm, an oil phase in which the prepolymer (U-1) (100 parts) andthe MEK ketimine compound (5.6 parts) were charged into a reactionvessel and then these components were mixed with each other, and anaqueous solution in which a dispersing agent (a sodium salt ofdodecyldiphenyl ether disulfonate) (5.3 parts) was dissolved were sentto this apparatus at flow rates of 100 kg/hour, and 400 kg/hour,respectively, to conduct the dispersion. This mixture was shifted to areaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube, and then the inside thereof was purged withnitrogen. While the mixture was stirred, the reactive components thereinwere caused to react with each other at 50° C. for 10 hours. After thetermination of the reaction, the resultant was separated by filtration,and then dried to produce urethane fine particles (G-7). The fineparticles (G-7) had a thermally softening temperature of 141° C., and acentral particle diameter of 3 μm. The particles were put into aHenschel Mixer, and stirred at 40 m/sec. to granulate the fine particles(G-7). After 15 minutes from the start of the stirring, the temperaturereached 140° C. After the driving of the apparatus was continued for 15minutes, the driving was stopped to yield urethane resin particles(P-7). The (P-7) had an Mn of 25,000, and a central particle diameter of350 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-7) were used, urethane resin particles (C-7)for slush molding were yielded.

Example 8

Production of Urethane Resin Particles (C-8):

Into a reaction vessel were charged the prepolymer (U-2) (100 parts),and the MEK ketimine compound (4.1 parts), and the components were mixedwith each other. Thereto was added 300 parts of an aqueous solution inwhich a dispersing agent (Sanspearl PS-8 (1.3 parts), manufactured bySanyo Chemical Industries, Ltd.) was dissolved. An ultra disperser wasused to mix these components with each other at a rotation number of6000 rpm for 1 minute. This mixture was shifted to a reaction vesselequipped with a thermostat, a stirrer and a nitrogen-blowing tube, andthen the inside thereof was purged with nitrogen. While the mixture wasstirred, the reactive components therein were caused to react with eachother at 50° C. for 10 hours. After the termination of the reaction, theresultant was separated by filtration, and then dried to produceurethane resin fine particles (G-8). The particles (G-8) had a thermallysoftening temperature of 140° C., and a central particle diameter of 40μm. The particles were put into a Henschel Mixer, and stirred at 40m/sec. to granulate the fine particles (G-8). After 15 minutes from thestart of the stirring, the temperature reached 140° C. At this time, thedriving was stopped to yield urethane resin particles (P-8). The (P-8)had an Mn of 25,000, and a central particle diameter of 110 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-8) were used, urethane resin particles (C-8)for slush molding were yielded.

Example 9

Production of Urethane Resin Particles (C-9):

Urethane resin particles (P-9) were yielded in the same way as inExample 1 except that the use amount of the tetrahydrofuran was changedto 34 parts (content of the organic solvent in the aqueous solution: 10%by weight). The (P-9) had an Mn of 25,000, and a central particlediameter of 120 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-9) were used, urethane resin particles (C-9)for slush molding were yielded.

Example 10

Production of Urethane Resin Particles (C-10):

Urethane fine particles (G-10) were yielded in the same way as inExample 7 except that the use amount of the dispersing agent (the sodiumsalt of dodecyldiphenyl ether disulfonate) was changed to 7.5 parts. Theparticles (G-10) had a thermally softening temperature of 141° C., and acentral particle diameter of 2 μm. Furthermore, urethane resin particles(P-10) were yielded in the same way as in Example 7. The (P-10) had anMn of 25,000, and a central particle diameter of 250 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-10) were used, urethane resin particles(C-10) for slush molding were yielded.

Example 11

Production of Urethane Resin Particles (C-11):

The following were mixed with 39.3 parts of 1,6-HG to preparehomogeneous glycol components: 243.5 parts of a polyester diol having anMn of 1000 yielded from 1,4-BD, and adipic acid; 243.5 parts of apolyester diol having an Mn of 2600 yielded from 1,4-BD, ethylene glycoland adipic acid; and 324.7 parts of a polyester diol having an Mn of1500 yielded from 1,6-HG and isophthalic acid. The glycol componentswere mixed with HDI, and the mixture was supplied at a flow rate ratioof 100:17.5 from a hopper of a biaxial extruder, the temperature ofwhich was adjusted to about 190° C. The mixture was kneaded, andsimultaneously resinified to yield a polyurethane resin.

The polyurethane resin yielded in the above-described step was put intoa pelletizer. To 100 parts of the pelletized polyurethane were added0.25 parts of Irganox 245 (manufactured by Ciba Specialty ChemicalsInc.) as an antioxidant, 0.15 parts of Tinuvin 213 (manufactured by CibaSpecialty Chemicals Inc.) as an ultraviolet absorbent, 0.15 parts ofTinuvin 765 (manufactured by Ciba Specialty Chemicals Inc.) as a lightstabilizer, and 0.25 parts of SH 200-1,000CS (manufactured by DowCorning Toray Co., Ltd.) as an internal releasing agent. The mixture wassupplied from a hopper of a biaxial extruder, the temperature of whichwas adjusted to about 200° C., and kneaded to yield a polyurethaneresin.

The polyurethane resin, to which the additives were added as describedabove, was cooled to −150° C. with liquid nitrogen, and then made into afine powder by means of an impact pulverizer. In order to give fluiditythereto, 0.4 parts of a dusting powder “MP-1451” was added to 100 partsof the resin, and then these components were stirred and mixed with eachother to cause the powder to adhere evenly onto the surface of thepolyurethane resin. Next, the resultant was passed through a sievehaving a mesh of 200 to yield urethane resin fine particles (G-11). The(G-11) had a thermally softening temperature of 110° C., and a centralparticle diameter of 50 μm. The particles were put into a HenschelMixer, and stirred at 40 m/sec. to granulate the fine particles (G-11).After 15 minutes from the start of the stirring, the temperature reached110° C. At this stage, the driving was stopped to yield urethane resinparticles (P-11). The (P-11) had an Mn of 25,000, and a central particlediameter of 180 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-11) were used, urethane resin particles(C-11) for slush molding were yielded.

Example 12

Production of Urethane Resin Particles (C-12):

Into a reaction vessel were charged 100 parts of the prepolymer solution(U-3) and 5.6 parts of the MEK ketimine compound. Thereto was added 500parts by weight of the dispersion medium (Y-1), and an ultra disperserwas then used to mix these components at a rotation number of 12000 rpm(peripheral speed: 20 m/s) for 1 minute. This mixture was shifted to areaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube. The inside of the vessel was purged withnitrogen, and then the reactive components therein were caused to reactwith each other at 50° C. for 10 hours while the mixture was stirred.After the termination of the reaction, the system was heated to 60° C.under reduced pressure to remove the solvent. After the removal of thesolvent, the resultant was separated by filtration, and then dried toproduce urethane fine particles (G-12).

The (G-12) had a central particle diameter of 7 μm, and a Cv of 91, andthe urethane resin (D-12) had an SP value of 11.2 and a thermallysoftening temperature of 137° C.

Furthermore, to 100 parts of the (G-12) prepared as described above wasdropwise added 5 parts of MEK (boiling point: 78° C.; difference betweenthe SP value thereof and that of the urethane resin (D-12): 2.2) as asolvent (T) while the particles (G-12) were stirred. In this way, theslurry was made into an even state. Thereafter, while the slurry wasstirred at a peripheral speed of 6.5 m/s by means of a high-speed mixermanufactured by Fukae Industries Co., Ltd., the temperature was raisedto 81° C. Thereafter, the temperature was immediately cooled to 50° C.while the slurry was stirred at a peripheral speed of 1.0 m/s. Thecentral particle diameter was measured. As a result, the centralparticle diameter was 50 μm. Thus, 5 parts of MEK were further sprayedthereon, and the temperature was raised to 81° C. This state wascontinued for 15 minutes. Thereafter, the temperature was immediatelycooled to 50° C. under the slurry was stirred at a peripheral speed of1.0 m/s. The central particle diameter was measured. As a result, thecentral particle diameter was 103 μm. Thus, the temperature was raisedto 55° C., and the solvent was distilled off under reduced pressure. Inthis way, urethane resin particles (P-12) were yielded. The resultant(P-12) had a central particle diameter of 103 μm, and a Cv of 34.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-12) were used, urethane resin particles(C-12) for slush molding were yielded.

Example 13

Production of Urethane Resin Particles (C-13):

Into a reaction vessel were charged 100 parts of the prepolymer solution(U-3) and 5.6 parts of the MEK ketimine compound. Thereto was added 340parts by weight of the dispersion medium (Y-1), and an ultra disperserwas then used to mix these components at a rotation number of 9000 rpm(peripheral speed: 15 m/s) for 1 minute. This mixture was shifted to areaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube. The inside of the vessel was purged withnitrogen, and then the reactive components therein were caused to reactwith each other at 50° C. for 10 hours while the mixture was stirred. Inthis way, produced was a slurry (R-13) containing urethane resin fineparticles (G-13).

The particles (G-13) had an average particle diameter of 22 μm, and a Cvof 70, and the urethane resin (D-13) had an SP value of 11.2 and athermally softening temperature of 141° C.

To 180 parts of the (R-13) prepared as described above was added 20parts of MEK (boiling point: 78° C.; difference between the SP valuethereof and that of the urethane resin (D): 2.2) as a solvent (T). Whilethe slurry was stirred at a peripheral speed of 15 m/s, the temperaturewas raised to 70° C. This state was continued for 1 hour. Thereafter,the solvent was distilled off under reduced pressure. The resultant wasseparated by filtration, washed and dried to yield urethane resinparticles (P-13). The resultant (P-13) had a central particle diameterof 155 μm, and a Cv of 25.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-13) were used, urethane resin particles(C-13) for slush molding were yielded.

Example 14

Production of Urethane Resin Particles (C-14):

Into a reaction vessel were charged 100 parts of the prepolymer solution(U-3) and 5.6 parts of the MEK ketimine compound. Thereto was added 340parts by weight of the dispersion medium (Y-1), and an ultra disperserwas used to mix these components at a rotation number of 7000 rpm(peripheral speed: 12 m/s) for 2 minutes. This mixture was shifted to areaction vessel equipped with a thermostat, a stirrer and anitrogen-blowing tube. The inside of the vessel was purged withnitrogen, and then the reactive components therein were caused to reactwith each other at 50° C. for 10 hours while the mixture was stirred.After the termination of the reaction, the system was heated to 60° C.under reduced pressure to remove the solvent. After the removal of thesolvent, the resultant was separated by filtration, and then dried toproduce urethane fine particles (G-14).

The (G-14) had an average particle diameter of 55 μm, and a Cv of 68,and the urethane resin (D-14) had an SP value of 11.2 and a thermallysoftening temperature of 142° C.

To 140 parts of the dispersion medium (Y-1) was dispersed 65 parts ofthe (G-14) prepared as described above while the medium (Y-1) wasstirred, to prepare a slurry (R-14). To this slurry (R-14) was added 15parts of THF (boiling point: 66° C.; difference between the SP valuethereof and that of the urethane resin (D): 2.1) as a solvent (T). Whilethe slurry was stirred at a peripheral speed of 1.0 m/s, the temperaturewas raised to 65° C. This state was continued for 3 hours. Thereafter,the solvent was distilled off under reduced pressure. The resultant wasseparated by filtration, washed and dried to yield urethane resinparticles (P-14). The resultant (P-14) had a central particle diameterof 137 μm, and a Cv of 27.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P-14) were used, urethane resin particles(C-14) for slush molding were yielded.

Example 15

Production of Urethane Resin Particles (C-15):

To 100 parts of the urethane resin particles (P-1) yielded in Example 1were added 1.0 part of a dibenzoic acid ester (H-1) (Sansoft EB300,manufactured by Sanyo Chemical Industries, Ltd., melting point: 0° C. orlower; boiling point: 300° C. or higher) of polyethylene glycol(polymerization degree: 2 to 10), and 1.0 part of dipentaerythritolpentaacrylate as additives to immerse the particles in the liquid at 70°C. for 1 hour. Thereto was added 3.0 parts of the pigment-dispersedresin particles (SE-1), and the resultant mixture was stirred in aHenschel Mixer at a rotation speed of 700 minutes⁻¹ for 1 minute (ratioof the particle diameter of the (P-15) to that of the (SE-1): 100:11).Next, the resultant was shifted to a Nauta Mixer. Thereinto were chargedtwo kinds of internally-additive releasing agents {adimethylpolysiloxane (0.06 parts) [KL45-10000, manufactured by NipponUnicar Co., Ltd.], and a carboxyl-modified silicone (0.05 parts)[X-22-3710, manufactured by Shin-Etsu Chemical Co., Ltd.]}, and thenthese components were mixed with each other for 1 hour. Thereafter, themixture was cooled to room temperature. Finally, thereto was charged ablocking inhibitor (0.5 parts) [Ganz Pearl PM-0305, manufactured by GanzChemical Co., Ltd.], and the components were mixed with each other. Themixture was passed through a sieve having a mesh of 48. From theresultant, particles passed through a sieve having a mesh of 200 werethen removed to yield urethane resin particles (C-15).

Comparative Example 1

Production of Urethane Resin Particles (C′-1):

Into a reaction vessel were charged the prepolymer solution (U-1) (100parts) and the MEK ketimine compound (5.6 parts), and these componentswere mixed with each other. Thereto was added 300 parts of an aqueoussolution in which a dispersing agent (Sanspearl PS-8 (1.3 parts)manufactured by Sanyo Chemical Industries, Ltd.) were dissolved. Anultra disperser manufactured by Yamato Scientific Co., Ltd. was thenused to mix these components at a rotation number of 5000 rpm for 1minute. This mixture was shifted to a reaction vessel equipped with athermostat, a stirrer and a nitrogen-blowing tube. The inside of thevessel was purged with nitrogen, and then the reactive componentstherein were caused to react with each other at 50° C. for 10 hourswhile the mixture was stirred. After the termination of the reaction,the resultant was separated by filtration, and then dried to produceurethane resin particles (P′-1). The (P′-1) had an Mn of 25,000, and acentral particle diameter of 150 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P′-1) were used, urethane resin particles(C′-1) for slush molding were yielded.

Comparative Example 2

Production of Urethane Resin Particles (C′-2):

The following were mixed with 1,6-HG (39.3 parts) to prepare homogeneousglycol components: a polyester diol (243.5 parts) having an Mn of 1000yielded from 1, 4-BD, and adipic acid; a polyester diol (243.5 parts)having an Mn of 2600 yielded from 1,4-BD, ethylene glycol, and adipicacid; and a polyester diol (324.7 parts) having an Mn of 1500 yieldedfrom 1,6-HG and isophthalic acid. The glycol components were mixed withHDI, and the mixture was supplied at a flow rate ratio of 100:17.5 froma hopper of a biaxial extruder, the temperature of which was adjusted toabout 190° C. The mixture was kneaded, and simultaneously resinified toyield a polyurethane resin.

The polyurethane resin yielded in the above-described step was put intoa pelletizer. To 100 parts of the pelletized polyurethane were added0.25 parts of Irganox 245 (manufactured by Ciba Specialty ChemicalsInc.) as an antioxidant, 0.15 parts of Tinuvin 213 (manufactured by CibaSpecialty Chemicals Inc.) as an ultraviolet absorbent, 0.15 parts ofTinuvin 765 (manufactured by Ciba Specialty Chemicals Inc.) as a lightstabilizer, and 0.25 parts of SH 200-1,000CS (manufactured by DowCorning Toray Co., Ltd.) as an internal releasing agent. The mixture wassupplied from a hopper of a biaxial extruder, the temperature of whichwas adjusted to about 200° C., and kneaded to yield a polyurethaneresin.

The polyurethane resin, to which the additives were added as describedabove, was cooled to about −150° C. with liquid nitrogen, and then madeinto a fine powder by means of an impact pulverizer. In order to givefluidity thereto, 0.4 parts of a dusting powder “MP-1451” was added to100 parts of the resin, and then these components were stirred and mixedwith each other to cause the powder to adhere evenly onto the surface ofthe polyurethane resin. Next, the resultant was passed through a sievehaving a mesh of 48. Furthermore, particles passed through a sievehaving a mesh of 200 were removed therefrom to yield polyurethane resinparticles (P′-2). The (P′-2) had a central particle diameter of 180 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P′-2) were used, urethane resin particles(C′-2) for slush molding were yielded.

Comparative Example 3

Production of Vinyl Chloride Resin Particles (C′-3):

Into a Henschel Mixer were charged 100 parts of a vinyl chloride resin(ZEST 1000Z, manufactured by Shin Dai-Ichi Vinyl Corporation), 2.7 partsof the pigment-dispersed liquid (HE-1), 5 parts of epoxidized soybeanoil (O-130P, manufactured by Adeka Corporation), 5 parts of hydrotalcite(Alcamizer-5, manufactured by Kyowa Chemical Industry Co., Ltd.), 1 partof zeolite (Mizukalizer DS, manufactured by Mizusawa IndustrialChemical, Ltd.), and 0.3 parts of stearoylbenzoylmethane (Karenz DK-1,manufactured by Showa Denko K.K.). These components were mixed eachother at a rotation number of 700 minutes⁻¹. When the temperature of themixture rose to 80° C., 80 parts of a plasticizer (Trimex NSK,manufactured by Kao Corporation) were added thereto. Thereafter, thesecomponents were mixed with each other until the plasticizer was absorbedto the vinyl chloride resin so that the mixture turned to a mixture ofdry and fine particles. In this way, vinyl chloride resin particles(C′-3) were yielded.

Comparative Example 4

Production of Urethane Resin Particles (C′-4):

Urethane fine particles (G′-4) were yielded in the same way as inExample 7 except that the use amount of the dispersing agent (the sodiumsalt of dodecyldiphenyl ether disulphate) was changed to 11.0 parts. Thefine particles (G′-4) had a central particle diameter of 1 μm. In thesame way as in Example 7, urethane resin particles (P′-4) were yielded.The (P′-4) had an Mn of 25,000, and a central particle diameter of 190μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P′-4) were used, urethane resin particles(C′-4) for slush molding were yielded.

Comparative Example 5

Production of Urethane Resin Particles (C′-5):

Urethane resin particles (P′-5) were yielded in the same way as inExample 5 except that the peripheral speed of the Henschel Mixer waschanged to 0.4 m/s. The (P′-5) had an Mn of 25,000, and a centralparticle diameter of 180 μm.

In the same way as in Example 1 except that instead of the (P-1) inExample 1, the particles (P′-5) were used, urethane resin particles(C′-5) for slush molding were yielded.

Production of Resin Molded Products (Q):

Slush molding was performed as follows: resin particles (C1) to (C15)and (C′1) to (C′5), for slush molding, according to Examples 1 to 15,and Comparative Examples 1 to 5 were filled into respectiveNi-electrocast molds which were each a mold having a crimped pattern andheated beforehand to 230° C. After 10 seconds, an extra of the resinpowdery composition was discharged from each of the molds. The mold wasnaturally cooled for 60 seconds, and then cooled with water. Theresultant was then removed from the Ni-electrocast mold. In this way,resin molded bodies (Q1) to (Q15) and (Q′1) to (Q′5) were yielded whichwere each a skin body.

In accordance with methods described below, evaluations were made aboutindividual physical properties of each of the urethane resin particles(C), the number of particles (F) which were each an aggregate of thepigment particles (E), the discoloration, and the skin bodies. Theresults are shown in Tables 1 and 2.

TABLE 1 Example Example Example Example Example 1 2 3 4 5 Urethane resin(D) Urea group % by weight 2.8 2.8 2.8 0 2.8 concentration Total ofurethane % by weight 11.4 11.4 11.4 11.9 11.4 group concentration + ureagroup concentration Melting point ° C. 215 215 215 126 215 Glasstransition ° C. −43 −43 −43 −55 −43 temperature Urethane resin particles(C) Central particle μm 151 180 180 20 500 diameter Shape factor SF1 188170 160 120 200 Shape factor SF2 152 148 138 131 150 Ratio of 90%particle 2.7 3.0 2.9 3.0 3.0 diameter to 10% particle diameterEvaluation results Flow-down period Seconds 17.5 18.0 17.0 20.0 11.2Powder fluidity ∘ ∘ ∘ ∘ ∘ Particles (F) each of The 0.25 0.50 0.25 0.001.00 which is aggregate number/100- particles Discoloration ∘ ∘ ∘ ∘ ∘Resin molded body (Q) Thickness mm 0.5 0.5 0.5 1.2 0.8 Evaluation ofpinholes ∘ ∘ ∘ ∘ ∘ Example Example Example Example Example 6 7 8 9 10Urethane resin (D) Urea group 2.6 2.8 2.6 2.8 2.8 concentration Total ofurethane 10.6 11.4 10.6 11.4 11.4 group concentration + urea groupconcentration Melting point 209 215 209 215 215 Glass transition −39 −43−39 −43 −43 temperature Urethane resin particles (C) Central particle143 350 110 120 250 diameter Shape factor SF1 170 110 180 101 110 Shapefactor SF2 151 199 120 120 240 Ratio of 90% particle 2.8 2.7 3.0 2.0 3.0diameter to 10% particle diameter Evaluation results Flow-down period16.8 13.0 18.0 14.5 13.0 Powder fluidity ∘ ∘ ∘ ∘ ∘ Particles (F) each of0.50 0.00 0.75 1.00 1.00 which is aggregate Discoloration ∘ ∘ ∘ ∘ ∘Resin molded body (Q) Thickness 0.7 0.6 0.7 0.5 0.5 Evaluation ofpinholes ∘ ∘ ∘ ∘ ∘

TABLE 2 Example Example Example Example Example 11 12 13 14 15 Urethaneresin (D) Urea group % by weight 0 1.0 1.0 1.0 2.8 concentration Totalof urethane group % by weight 10.5 9.7 9.7 9.7 11.4 concentration + ureagroup concentration Melting point ° C. 175 195 195 195 215 Glasstransition ° C. −45 −39 −39 −39 −43 temperature Urethane resin particles(C) Central particle μm 200 103 155 137 151 diameter Shape factor SF1200 190 185 190 188 Shape factor SF2 240 180 220 210 152 Ratio of 90%particle 3.0 2.9 2.8 2.9 2.7 diameter to 10% particle diameterEvaluation results Flow-down period Seconds 19.5 16.0 18.0 18.0 17.0Powder fluidity ∘ ∘ ∘ ∘ ∘ Particles (F) each of The 0.75 0.75 1.00 0.750.25 which is aggregate number/100- particles Discoloration ∘ ∘ ∘ ∘ ∘Resin molded body (Q) Thickness mm 1.0 0.8 0.8 0.8 0.7 Evaluation ofpinholes ∘ ∘ ∘ ∘ ∘ Comparative Comparative Comparative ComparativeComparative Example 1 Example 2 Example 3 Example 4 Example 5 Urethaneresin (D) Urea group 2.8 0 0 2.8 2.8 concentration Total of urethanegroup 11.4 10.5 0 11.4 11.4 concentration + urea group concentrationMelting point 215 175 145 215 215 Glass transition −43 −45 −50 −43 −43temperature Urethane resin particles (C) Central particle 150 180 180190 180 diameter Shape factor SF1 125 210 130 200 220 Shape factor SF2110 240 120 260 220 Ratio of 90% particle 3.5 6.5 — 2.7 4.0 diameter to10% particle diameter Evaluation results Flow-down period 13.0 24.6 17.314.0 24.0 Powder fluidity ∘ x ∘ ∘ x Particles (F) each of 2.25 0.75 0.501.50 0.75 which is aggregate Discoloration x ∘ ∘ x ∘ Resin molded body(Q) Thickness 0.5 1.0 1.2 1.0 0.5 Evaluation of pinholes ∘ x ∘ ∘ x

<Shape Factors SF1 and SF2>

In the measurement of the shape factors SF1 and SF2, the particles werephotographed under 300 magnifications through a scanning electronmicroscope (S-800, manufactured by Hitachi Ltd.) when the particles hada central particle diameter of 20 μm or more and less than 40 μm; under160 magnifications when the particles had a central particle diameter of40 μm or more and less than 75 μm; under 80 magnifications when theparticles had a central particle diameter of 75 μm or more and less than150 μm; under 40 magnifications when the particles had a centralparticle diameter of 150 μm or more and less than 300 μm; and under 25magnifications when the particles had a central particle diameter of 300μm or more. From the resultant images (resolution: 128q0×1024 pixels),80 particles were selected at random. The selected particles wereintroduced into an image analyzer (LUSEX3, manufactured by NirecoCorporation) to make an analysis. In this way, the average SF1 value,and the average SF2 value were calculated out.

<Central Particle Diameter>

A Microtrac HRA Particle Size Analyzer 9320-X100 (manufactured byNikkiso Co., Ltd.) was used to measure the below-sieve 50% particlediameter by a laser-light scattering method, and the resultant value wasdefined as the central particle diameter thereof.

<Ratio of 90% Particle Diameter to 10% Particle Diameter>

A Microtrac HRA Particle Size Analyzer 9320-X100 (manufactured byNikkiso Co., Ltd.) was used to measure the below-sieve 90% particlediameter, and the below-sieve 10% particle diameter by a laser lightscattering method, and then the ratio of the 90% particle diameter tothe 10% particle diameter was calculated out.

<Glass Transition Temperature>

For the glass transition temperature of the resin, a dynamicviscoelastometer, Rheogel-E4000 manufactured by UBM, was used to measurethe dynamic viscoelasticity while the temperature of the system wasraised at a constant rate under conditions described below. Thetemperature of the top of a peak of the loss modulus E″ was defined asthe glass transition temperature.

-   Measuring conditions:-   Frequency: 10 Hz-   Temperature range: −90 to 140° C., and-   Temperature-raising rate: 5° C./minute

<Melting Point>

A flow tester, CFT-500 manufactured by SHIMADU CORPORATION, was used toraise the temperature of the resin at a constant rate under conditionsdescribed below, and the temperature at which the outflow amount turnedto ½ of the total amount was defined as the melting point.

-   Load: 5 kg-   Die: 0.5 mmφ−1 mm-   Temperature-raising rate: 5° C./minute

<Flow-Down Period>

A bulk density meter (in accordance with JIS-K6720) manufactured byTsutsui Scientific Instruments Co., Ltd. was used to measure a periodwhen 100 cm³ of the material flowed down through a funnel. The resultantvalue was used as an index of the powder fluidity. Those having aflow-down period of 20 seconds or less were judged to be acceptableabout powder fluidity.

<Number of Particles (F) Which were Each Aggregate of Pigment Particles(E)>

A microscope was used to observe, under 100 magnifications, the surfacesof the resin particles, the total number of the particles being 400. Ona monitor in which an image thereof was projected under 100magnifications, a count was made about the number of particles (F)observed with the naked eye, the particles (F) being each an aggregateof the pigment particles (E).

<Discoloration>

The temperature of the front surface of an A4-size iron plate put on ahot plate was set to 250° C. Thereafter, 50 g of the resultant resinparticles was put onto the plate. In order to make the film thickness ofthe particles even, the surface was leveled. After 90 seconds therefrom,the system was put into a water bath having a temperature of 25° C. tobe cooled. The leveled resin film was peeled from the iron plate. Fromthe film, a test piece was cut off which had a width of about 40 mm anda length of about 200 mm. The piece was attached to a plane abrasiontester (manufactured by Suga Test Instruments Co., Ltd.; model No.:FR-T), and its abrader was covered with a white cotton cloth, and thenthe cloth was fixed thereto. The load of the abrader was set to 300 g.The abrader was reciprocated 100 times on the test piece, and then thetest piece was evaluated about discoloration. When the white cottoncloth was not colored, the test piece was estimated to be good (◯). Whenthe cloth was colored, the test piece was estimated to be bad (×).

<Pinhole Resistance>

The surface of each of the resultant molded bodies (Q) was observed witha microscope (under 10 magnifications), and then a situation as towhether or not pinholes were generated was examined. When the body had20 or less pinholes in its area of 10 cm×10 cm, the body was estimatedto be good (◯) about pinhole resistance.

In Tables 1 and 2 are shown the results of the above-describedevaluations. In general, the fluidity of a powder depends on the centralparticle diameter and the particle shape thereof. A comparison ofExample 3 with Comparative Example 3 has made it clear that when therespective central particle diameters thereof are equivalent to eachother, the urethane resin shows powder fluidity equivalent to that ofthe vinyl chloride resin particles although the urethane resin has alarger shape factor SF1. Moreover, in the urethane resin particles ofthe present invention, the generation amount of the particles (F), whichare each a pigment-aggregate, is very small; thus, when the presentparticles are used as a material for molding, the material is good incolor-developability, and makes it possible to decrease the amount ofalien substances. Furthermore, the present particles are good in theperformance of dispersing a pigment ; thus, even when the molded body iswiped with a cloth or some other, the shift of the color or some otherdefect is hardly generated. Thus, the molded body is a high-qualitymolded body.

When the urethane resin particles of the present invention for slushmolding are used to perform slush molding, a skin body is obtained whichis a high-quality molded body in which inconveniences such as pinholesand underfill are hardly caused.

Industrial Applicability

The urethane resin particles of the present invention for slush moldingare excellent in power fluidity, thermal meltability, flexibility andendurance; thus, the particles can be used suitably as a material usefulfor slush molding.

The invention claimed is:
 1. Urethane resin particles (C) for slushmold, comprising; urethane resin particles (P) of a urethane resin (D),and pigment particles (E) consisting of a pigment, wherein the pigmentparticles (E) adhere onto the surfaces of the urethane resin particles(P), wherein the urethane resin particles (C) have a shape factor SF1 of101 to 200, a shape factor SF2 of 120 to 240, and a central particlediameter of 20 to 500 μm.
 2. The resin particles (C) according to claim1, which are granulated.
 3. The resin particles (C) according to claim1, wherein the ratio of the 90% particle diameter to the 10% particlediameter is from 2.0 to 3.0.
 4. The resin particles (C) according toclaim 1, wherein the urethane resin (D) has a concentration of ureagroups of 0.5 to 10% by weight, a total of the concentration of urethanegroups and that of the urea groups of 4 to 20% by weight, a meltingpoint of 160 to 260° C. and a glass transition temperature of −65 to 0°C.
 5. The resin particles (C) according to claim 1, wherein the urethaneresin (D) is a thermoplastic urethane resin yielded by causing anisocyanate group-terminated urethane prepolymer (a) derived from analiphatic diisocyanate (a1), a monool (a2), a high molecular weight diol(a3) having a number-average molecular weight of 500 to 10,000, and alow molecular weight diol (a4) if necessary to react with an alicyclicdiamine and/or an aliphatic diamine (b).
 6. The resin particles (C)according to claim 1, wherein aggregation of the pigment particles arehardly generated such that one piece or less of an aggregate of thepigment particles (E) having a particle diameter of 20 to 140 μm isincluded per one hundred of the urethane resin particles (P).
 7. Theresin particles (C) according to claim 1, further comprising an organiccompound (H), wherein the pigment (E) and the organic compound (H) forma pigment-dispersed liquid (HE) in which the pigment particles (E) aredispersed in the organic compound (H), wherein the organic compound (H)has a melting point of 0° C. or lower and a boiling point of 170° C. orhigher, and contains in the molecule thereof at least one ester group,wherein the pigment-dispersed liquid (HE) adhere onto the surfaces ofthe urethane resin particles (P).